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Our Top Recommended Big Brake Upgrade Kits For Your Audi S4
The S4 is a heavy four wheel drive saloon with a lot of engine sitting over the front axle, so it works its front brakes harder than the numbers suggest. It is also one of the few cars where our own price list needs explaining before you look at it, because on the S4 the ladder runs backwards in two places: the 360mm Monster 4 costs less than the 335mm, and the 380mm Mega Monster costs less than the 360mm. Those are not typos, and we are not going to quietly point you at the dearer one.
The other thing to settle first is which S4 you have. Tarox list their kit for the B5 2.7 Biturbo specifically. HiSpec list theirs against the S4 without naming a generation, and the entry 325mm kit is listed for the A4 and the S4 together. Get that conversation out of the way before the wheel one. Everything below comes from the three brands we stock for this car: Tarox in northern Italy, HiSpec Motorsport in Dartford, and Brembo, who make kits for the S4 across both axles from the B5 to the B9. The full S4 range is on the site if you want to browse it raw.
- Seven HiSpec kits, one Tarox kit and 32 Brembo kits cover the S4, spanning B5 to B9, front and rear, from £1,310 to £8,906 inc VAT
- The price ladder runs backwards twice, and both are called out below
- Tarox list their S4 kit for the B5 2.7 Biturbo, so tell us your generation before ordering
- Tarox arrive with braided hoses and Corsa pads already fitted; HiSpec price theirs separately so you choose the compound
What is on this page
- Three brands
- Wheel sizes: real numbers
- HiSpec 325mm Billet 4
- HiSpec Monster 4, 335mm and 360mm
- Tarox 330mm Super Sport
- HiSpec Monster 6, 335mm and 360mm
- HiSpec Mega Monster, 360mm and 380mm
- Brembo GT: front and rear across four S4 generations
- Which S4, and the A4 crossover
- What is in each box
- Every kit compared
- Common questions
- What we would actually fit
Three brands, three routes to a bigger brake kit
All three machine their own calipers from billet aluminium and build every kit to the car. Where they differ is what is in the box, how it is priced, and how long it takes to arrive.
Tarox
Built at the factory in northern Italy. Calipers are CNC machined from European billet alloy and hand assembled, discs are heat treated and hand balanced to 0.05mm. The S4 listing is a Super Sport kit for the B5 2.7 Biturbo and it arrives complete: vehicle specific braided hoses and Corsa pads already fitted. Tarox state full compatibility with ABS and ESP.
HiSpec Motorsport
Machined in Dartford from 6082 T6 billet aluminium, calipers and pistons both. Seven S4 kits covering three caliper families, made to order in Dartford, up to 28 working days: Billet 4, Monster 4 and 6, and Mega Monster. Made to order in up to 28 working days, with calipers in black, red, blue, gold or silver. Pads and braided hoses are priced separately so you pick the compound.
Brembo
Built at Brembo's Curno factory in Italy. The S4 range spans front kits from 332mm to 380mm and rear kits from the B5 through to the B9, covering four caliper families: GT-A, GT-M, GT-BM and GT-R. Made to order with a six to eight week lead time. Disc face (cross-drilled or Type 3 slotted) and caliper colour are chosen at order time at no extra cost. Pads and braided hoses are included.
Wheel sizes: real numbers for every kit
Minimum wheel diameter is a property of the kit and not of the car: a disc is a disc and a caliper is a caliper, so a figure published against one car holds for every car that kit is listed against. The HiSpec figures below come from their published data and the Tarox figure was looked up from their own product page for this exact kit. The only check that stays a conversation is depth, because a wheel of the right diameter can still foul a caliper at the spokes. Give Cameron the make and model of the wheel alongside the size and he will confirm before anything goes to build.
| Kit | Disc | Smallest wheel |
|---|---|---|
| HiSpec 325mm Billet 4 | 325mm | 17 inch |
| Tarox 330mm Super Sport | 330mm | 17 inch |
| HiSpec 335mm Monster 4 | 335mm | 17 inch |
| HiSpec 335mm Monster 6 | 335mm | 17 inch |
| HiSpec 360mm Monster 4 | 360mm | 18 inch |
| HiSpec 360mm Monster 6 | 360mm | 18 inch |
| HiSpec 360mm Mega Monster | 360mm | 18 inch |
| HiSpec 380mm Mega Monster | 380mm | 19 inch |
| Brembo GT front (all generations) | 332mm to 380mm | Clearance drawing on each product page (A, B and C dimensions); GT-R caliper needs more space than GT-S at the same disc size |
| Brembo GT rear (all generations) | Varies by generation | Clearance drawing on each product page |
HiSpec 325mm Billet 4: the entry kit, and the one shared with the A4
This is the cheapest way into a proper big brake conversion on the S4, and the only kit on this page listed for the A4 as well. The Billet 4 is the caliper HiSpec make most of: four pistons, machined from 6082 T6 billet aluminium, with external boots to keep road grime out of the seals. At 325mm it clears a 17 inch wheel, which most S4s are already on.
Pads and braided hoses are priced separately, which keeps the entry number down and lets you pick the compound to suit how the car gets used. If the S4 is mostly a road car that sees the odd track evening, this is a lot of brake for the money.
- £1,470.00 inc VAT
- Fits behind 17 inch wheels
- 325mm disc, four piston Billet 4 caliper
- Listed for the Audi A4 as well as the S4
- Pads and braided hoses priced separately, five caliper colours, up to 28 working days
HiSpec Monster 4, 335mm and 360mm: where the price runs backwards
The Monster is the step up from the Billet 4: a longer pad and higher temperature seals, which is what earns its money once the brakes are getting properly hot. HiSpec list it for the S4 at 335mm and 360mm, and here is the part worth reading twice. The 360mm kit is £1,635.00 and the 335mm kit is £1,650.00, so the bigger disc is the cheaper kit by fifteen pounds.
We are not going to pretend that makes sense, and we are certainly not going to point you at the smaller one at the higher price. If your wheels are 18 inch or bigger, take the 360mm and keep the fifteen pounds. The only reason to take the 335mm is that you are on 17s and the 360mm will not fit, which is a real reason and the whole point of the table above.
- 360mm at £1,635.00, 335mm at £1,650.00, both inc VAT
- 360mm needs 18 inch wheels, 335mm clears 17 inch
- Monster 4 caliper, longer pad and higher temperature seals than the Billet 4
- The bigger disc is the cheaper kit, so buy on wheel size
- Pads and braided hoses priced separately
Tarox 330mm Super Sport: the complete kit in one box
If you want one box with nothing left to source, this is it, and it is the only Tarox kit currently in stock for the S4. The B34GT caliper uses sequentially sized pistons so the pad wears evenly across its face and the pedal stays consistent as heat goes into it. The 330mm two piece floating disc is balanced to 0.05mm at the factory, and the kit arrives with vehicle specific braided hoses and Corsa pads already fitted. Minimum wheel is 17 inch.
One note on the listing, because we would sooner say it than have you counting pistons when it arrives. The title says 10pot. That was the older B34 caliper design. The current B34GT runs eight sequential pistons, our own description says eight, and eight is what turns up. Tarox list this kit for the B5 2.7 Biturbo, so confirm your generation with us before ordering.
- £2,365.30 inc VAT, complete
- Fits behind 17 inch wheels
- Corsa pads and braided hoses included and fitted
- B34GT caliper, 8 sequential pistons despite the 10pot in the title
- 330mm two piece floating disc, balanced to 0.05mm
HiSpec Monster 6, 335mm and 360mm: the track pick
Six pistons instead of four, which spreads the clamping load over a longer pad and keeps the pressure more even across it as the pad wears. On a car as heavy as an S4 doing repeated hard stops, that is the difference you feel late in a session instead of on the first lap. Both sizes are here: 335mm on 17 inch wheels at £1,740.00, and 360mm on 18 inch at £1,863.00.
This is the range Garreth would point a genuine track day S4 at. The Billet 4 is plenty for the road, and the Monster 6 is what you want when the car is doing session after session and you have stopped worrying about the last two hundred pounds.
- 335mm at £1,740.00, 360mm at £1,863.00, both inc VAT
- 335mm clears 17 inch, 360mm needs 18 inch
- Six piston Monster caliper, longer pad than the Billet 4
- Pads and braided hoses priced separately, so pick a track compound
- Five caliper colours, made to order in the UK, up to 28 working days
HiSpec Mega Monster, 360mm and 380mm: the biggest kits listed
The Mega Monster is the largest caliper HiSpec list for the S4 and it comes at 360mm and 380mm. This is the second place the price ladder runs backwards: the 380mm kit is £2,159.69 and the 360mm is £2,196.85, so once again the bigger disc is the cheaper one, this time by thirty seven pounds.
The catch is the wheel. The 380mm needs a 19 inch wheel and the 360mm clears an 18, so this one is genuinely decided by what is on the car. If you are on 19s, take the 380mm and enjoy paying less for more. If you are on 18s, the 360mm is your kit and the extra thirty seven pounds is simply what it costs.
- 380mm at £2,159.69, 360mm at £2,196.85, both inc VAT
- 380mm needs 19 inch wheels, 360mm needs 18 inch
- Mega Monster caliper, the largest HiSpec list for this car
- The bigger disc is again the cheaper kit
- Pads and braided hoses priced separately
Brembo GT: front and rear across four S4 generations
Brembo cover the S4 from the B5 right through to the B9, front and rear. HiSpec and Tarox are front axle only. If you want a matched set from one manufacturer across both ends, Brembo are the only option on this page.
The front range for a B6 or B7 opens at the GT-M: 365mm, six piston monobloc caliper, at £4,295.95. Step up to the GT-S billet version at £4,400.74, or go to the full GT-R at £8,329.97. On the B5 the front discs are 355mm in the same caliper families. On the B8 and B9 the discs step to 380mm, with prices from £4,662.68 for a GT-M to £8,906.26 for a GT-R.
Rear kits start at £1,309.74 for the GT-A on the B5 and go up to £7,439.34 for the GT-R rear on the B8. All Brembo kits are made to order in Italy, six to eight weeks from placing the order. Cross-drilled or Type 3 slotted disc face costs the same either way, and caliper colour is a free option set when you order.
Brembo publish their own caliper clearance drawings on each product page, with the A, B and C dimensions for the caliper body. Give Cameron the wheel make and model and he will go through the drawing with you before anything is ordered. The GT-R caliper body is physically larger than the GT-S at the same disc size, so those two need different wheel clearance. Ring us on 0115 9893488 before ordering.
- B6/B7 GT-M front 365mm 6 pot at £4,295.95 inc VAT; GT-S billet at £4,400.74; GT-R billet at £8,329.97
- B5 front kits at 355mm in the same caliper order; B8/B9 front at 380mm from £4,662.68 to £8,906.26
- B5 rear GT-A (1 pot) at £1,309.74; B6/B7 rear GT-A 345mm at £3,719.68; B8 rear GT-R at £7,439.34
- Made to order in Italy: six to eight weeks from order to delivery
- Cross-drilled or Type 3 slotted at the same price; caliper colour is a free option
- Brembo caliper clearance drawings on each product page; GT-R caliper needs more space than GT-S at same disc size
Which S4, and the A4 crossover
Worth settling before you order anything. Tarox name the B5 2.7 Biturbo on their S4 listing, so on a later car that kit is a conversation with us instead of a click. The HiSpec listings name the S4 without specifying a generation, and the 325mm Billet 4 is listed for the A4 and the S4 together, which tells you the front hub package is shared across more of the range than the badge suggests.
None of that is a reason to guess. Tell us the year and the engine, and if you can, the diameter of the disc that is on the car now. Cameron will confirm the fitment with the maker before anything is built, and on a made to order kit that is the five minutes that matters most.
What is actually in each box
The headline gap between HiSpec and Tarox closes once both are specced to the same level. HiSpec price their kits without pads or braided hoses. Tarox include both. Brembo include pads and hoses too, and are also made to order, so factor in the lead time alongside the price. Compare finished builds, not entry prices.
| In the box | HiSpec | Tarox | Brembo |
|---|---|---|---|
| Calipers | Billet 4, Monster 4 or 6, or Mega Monster, all 6082 T6 billet aluminium | B34GT billet alloy, hand assembled, 8 sequential pistons | GT-A two-piece or GT-M/GT-S/GT-R monobloc or billet; front four to six piston, rear one or four piston depending on spec |
| Discs | Sized to the kit, 325mm to 380mm | Two piece floating, balanced to 0.05mm | Front 332mm to 380mm, rear varies by generation; cross-drilled or Type 3 slotted at the same price |
| Brackets and hardware | Included | Included | Included |
| Braided hoses | Priced separately | Included | Included |
| Pads | Priced separately, your choice of compound | Corsa pads, fitted | Included |
| Caliper finish | Black, red, blue, gold or silver | Black, red, blue, green or gold anodised | Multiple colours, free option at order time |
| Built in | Dartford, UK, up to 28 working days | Northern Italy | Curno, Italy; six to eight weeks to order |
Every kit on this page compared
| Kit | Disc | Caliper | Smallest wheel | Pads and hoses | Price inc VAT |
|---|---|---|---|---|---|
| HiSpec Billet 4 | 325mm | 4 piston | 17in | Extra | £1,470.00 |
| HiSpec Monster 4 | 360mm | 4 piston | 18in | Extra | £1,635.00 |
| HiSpec Monster 4 | 335mm | 4 piston | 17in | Extra | £1,650.00 |
| HiSpec Monster 6 | 335mm | 6 piston | 17in | Extra | £1,740.00 |
| HiSpec Monster 6 | 360mm | 6 piston | 18in | Extra | £1,863.00 |
| HiSpec Mega Monster | 380mm | Mega Monster | 19in | Extra | £2,159.69 |
| HiSpec Mega Monster | 360mm | Mega Monster | 18in | Extra | £2,196.85 |
| Tarox Super Sport | 330mm, 2P | B34GT, 8 piston | 17in | Included | £2,365.30 |
| Brembo GT-A rear B5 (1 pot) | See product page | 1 piston GT-A | See product page | Included | £1,309.74 |
| Brembo GT-A front B5 (332mm, 4 pot) | 332mm | 4 piston GT-A | See product page | Included | £3,719.68 |
| Brembo GT-M front B6/B7 (365mm, 6 pot) | 365mm | 6 piston GT-M | See product page | Included | £4,295.95 |
| Brembo GT-S front B6/B7 (365mm, 6 pot) | 365mm | 6 piston GT-S billet | See product page | Included | £4,400.74 |
| Brembo GT-BM front B8/B9 (380mm, 6 pot) | 380mm | 6 piston GT-BM | See product page | Included | £4,767.47 |
| Brembo GT-R rear B8 (380mm, 4 pot) | 380mm | 4 piston GT-R billet | See product page | Included | £7,439.34 |
| Brembo GT-R front B6/B7 (365mm, 6 pot) | 365mm | 6 piston GT-R billet | See product page | Included | £8,329.97 |
Prices include VAT and were correct on 20 September 2026. The table is sorted by price. HiSpec and Tarox kits are sorted by disc size within each caliper family; Brembo rows are listed after. The Brembo rear GT-A at £1,309.74 sits below the HiSpec Billet 4 in price but is a rear kit, not comparable to a front conversion.
Common questions
Why is the bigger disc cheaper on two of these kits?
We do not have a tidy answer, and we would sooner show you the prices than hide them. The 360mm Monster 4 lists below the 335mm, and the 380mm Mega Monster lists below the 360mm. Both were checked against our live pricing on 22 August 2026. Where the bigger kit is cheaper and your wheels will clear it, buy the bigger kit. Where your wheels will not clear it, the smaller kit is the right one and the price is simply what it is. Ring us if it looks wrong on the day and we will confirm before you pay.
Will these fit my S4 if it is not a B5?
The Tarox kit is listed for the B5 2.7 Biturbo, so on a later car that one needs confirming with us first. The HiSpec kits are listed against the S4 without naming a generation. Either way, tell us the year and the engine and we will confirm the fitment with the maker before anything is built. These are made to order kits, so five minutes of checking beats a wrong caliper turning up in four weeks.
What is the difference between Billet 4, Monster and Mega Monster?
Pad size and heat capacity, mostly. The Billet 4 is the four piston road caliper and it is plenty for a fast road S4. The Monster 4 and Monster 6 run a longer pad with higher temperature seals, which is what you want for repeated hard stops on track, and the 6 spreads the load over more pistons for more even pad wear. The Mega Monster is the largest in the range and pairs with the biggest discs. On a car as heavy as an S4, the Monster range is the sensible middle.
Why are pads and hoses extra on the HiSpec kits?
HiSpec price the hardware bare so you choose the compound to match how the car is used: a softer road pad for a daily driver, something more aggressive for track evenings. Both pads and braided hoses can be added at the same time. We will quote the finished build level so you can compare it properly against the Tarox kit, which includes both as standard.
Is Brembo worth the extra over HiSpec and Tarox?
On a road S4 the Monster 6 at £1,863.00 is already a serious upgrade and the right answer for most people. Brembo make a different case: they are the only brand we stock making rear kits for the S4, and if the plan is regular circuit work on a B6, B7 or B8, a matched set front and rear from one manufacturer is cleaner than two separate upgrades. The GT-M front at £4,295.95 pairs with a GT-A rear to give you both axles sorted. If the car is road only or doing occasional track evenings, Garreth would point you at the Monster 6 and keep the difference in your pocket. Ring 0115 9893488 and we will work through the options with you.
How long before it arrives?
HiSpec kits are made to order in Dartford, so allow up to 28 working days. The Tarox kit is built at the factory in Italy and lead times vary through the year, so ask when you place the order and we will give you the current picture. Brembo kits are made to order in Italy, six to eight weeks from placing the order. None of these brands keep finished S4 kits on a shelf.
What we would actually fit
On an S4 that is mostly a road car on 17 inch wheels, the 325mm Billet 4 at £1,470.00, with pads and hoses budgeted at the same time. If the car is on 18s and you want the sensible upgrade, take the 360mm Monster 4 at £1,635.00, because it is both the bigger disc and the cheaper of the two Monster 4 kits, which is not a sentence we get to write often. For a car doing regular track work, the Monster 6 at 335mm or 360mm depending on your wheels. On 19s with a budget, the 380mm Mega Monster at £2,159.69 undercuts the 360mm version.
And if you want one box with the pads and hoses already in it and nothing left to source, the Tarox 330mm Super Sport, subject to confirming your generation. For a car doing proper circuit miles with the budget to match, Brembo are the only brand on this page covering both axles. The GT-M front at £4,295.95 and a GT-A rear is where Garreth would start that conversation, eight weeks in the build queue. Ring us on 0115 9893488 with your year, your engine and your wheel size. Working out what clears and what fouls is Cameron’s corner of the business, so have the wheel make and model handy and you will get a straight answer.
What is the best big brake kit for an Audi S4?
For a road-biased S4 on 17 inch wheels the HiSpec 325mm Billet 4 is the sensible starting point. If you want a genuine track kit, step up to the HiSpec Monster 6, and if you’d rather have pads and hoses already fitted in one box the Tarox 330mm Super Sport does that, just confirm your S4 is the B5 2.7 biturbo before ordering.
Whichever kit you’re looking at, send us your wheel make and model rather than just the size. Spoke shape varies enough between 17 inch wheels that diameter alone doesn’t tell us if it’ll clear.