Power by stage
Stock is Mercedes' rating (476 PS for the C63, 510 PS for the C63 S). Stage 1 to 4 are the tuners' own engine figures, in hp or PS (1 PS is 0.986 hp), on 93 US or 98 RON fuel. Real results depend on fuel, weather and the individual car.
Names with an arrow go straight to that part's product page for this car. Names in a dashed outline are other brands that make the part; exact links for them are being added.
Software: engine, torque module and gearbox
550–611 hpSoftware alone takes a C63 to about 550–611 hp, and because the C63 and C63 S share their hardware, the same tune fits both. On 2019-on cars it is more work: Weistec says the CPC module holds torque limiters, and "many 2020-2022 will not gain any power from an ECU tune if the CPC is not also upgraded", and Litchfield says some 2019-on cars need the engine computer plugged in directly, about six hours.
Typical cost: remaps €990 (BR-Performance), £720–£1,440 (Litchfield) or $1,999–$3,280 (Weistec, RENNtech); CPC upgrade for 2019-on cars $1,699 (Weistec); plug-in modules $767 (RaceChip) or €3,799 (DTE).List prices, Sept 2026, before shipping, import tax and fitting.
Stage 1 tunes compared
| Tune | Fuel | Claimed power | Claimed torque | Notes |
|---|---|---|---|---|
| Posaidon M177 software | 98 RON | 611 PS | 800 Nm | CPC software included depending on year |
| Weistec W.1 | — | 605 hp | 624 lb-ft | Estimated at the engine; 2019-on cars need the CPC too |
| RENNtech ECU+ | 93 US | 601 hp | 657 lb-ft | 517 whp measured; flashed through the diagnostic port |
| MSL Performance Stage 1 | — | up to 600 bhp | +100 lb-ft | Gearbox software recalibrated too |
| BR-Performance Stage 1 | not E85 | 570–575 PS (550 PS with GPF) | 820 Nm | Separate files for particulate-filter cars |
| Litchfield Stage 1 | — | around 570 bhp | around 580 lb-ft | Speed limiter removed |
| DTE PowerControl X | — | +86 PS (C63 S) / +114 PS (C63) | +117 / +166 Nm | Plug-in module, 3-year engine warranty |
| RaceChip GTS 5 Black | — | +91 hp (C63 S) | +95 lb-ft | Plug-in module |
Recommended with Stage 1
- CPC torque-module upgrade 2019-on cars
Weistec CPC (with its ECU tune)Posaidon
Without it a later car's tune is capped. Pre-2019 cars have no CPC.
- Gearbox (TCU) software recommended
Weistec 7-speed TCU tuneWeistec 9-speed TCU tuneBR-Performance
Higher clutch pressure and torque limits for the extra torque.
Downpipes, intake and cooling
590–667 hpStage 2 adds downpipes and an intake with a Stage 2 file. Weistec claims 667 hp with its downpipes and tune, and MSL "up to a mighty 630 bhp". The M177 cools its charge air with water, so a bigger front heat exchanger matters more than on most cars, especially in a hot summer.
Typical cost: downpipes $3,079 (Weistec) or £2,180.34–£5,746.14 (Milltek, track-only or with sports cats); CSF heat exchanger $749; Weistec airboxes $1,499; RENNtech R1 package $6,880.List prices, Sept 2026, before shipping, import tax and fitting.
Stage 2 packages compared
| Package | Fuel | Claimed power | Claimed torque | Required hardware |
|---|---|---|---|---|
| Weistec downpipes + tune | — | 667 hp | 642 lb-ft | Weistec downpipes |
| MSL Performance Stage 2 | — | up to 630 bhp | — | Downpipes, "essential" |
| RENNtech R1 | 93 US | 611 hp | 672 lb-ft | ECU tune, sport mufflers, blow-off adapters |
| BR-Performance Stage 2 | not E85 | 590 PS (570 PS with GPF) | 840–850 Nm | Hardware sent by e-mail |
Parts list
- Downpipes required
Weistec M177 downpipesMilltek downpipesRENNtech
Milltek sells a pair with high-flow sports catalysts as well as a catalyst-delete pair "for track use only".
- Front heat exchanger recommended
CSF #8088 heat exchanger
A 42 mm core against the stock 26 mm; CSF cites up to 68% lower intake temperatures in Regal Autosport's testing.
- Intake recommended
Eventuri carbon intakeWeistec carbon airboxes
Eventuri claims +10–12 hp on a stock car and +22–30 hp on a Stage 2 car.
- Exhaust optional
Akrapovič Evolution LineMilltek rear silencersRENNtechArmytrix
Akrapovič's titanium system is ECE approved, saves 13 kg and claims +8 PS.
- Water-methanol injection optional
Weistec water-methanol kit
Weistec claims "20-80 HP Gain (with proper tuning)" and less heat soak.
Upgraded turbos, fuel and gearbox
700–820 hpStage 3 upgrades the two turbos inside the V8's hot vee, with more fuel and gearbox work. Posaidon's RS700 claims 700 PS on 98 RON and TTE says its TTE760+ turbos are "Proven at 780HP using 98RON"; RENNtech's turbo packages claim 709 and 767 hp, and Weistec's W.3 820 hp.
Typical cost: turbos €2,940.33 before VAT (TTE760+), $2,995 send-in (Pure900) or $5,499 (Weistec W.3); RENNtech turbo packages $13,840–$23,880; fuel pumps $4,280 (RENNtech).List prices, Sept 2026, before shipping, import tax and fitting.
Turbo upgrades compared
| Kit | Fuel | Claimed power | Claimed torque | Notes |
|---|---|---|---|---|
| Posaidon RS700 / RS700+ | 98 RON | 700 / 780 PS | 890 / 980 Nm | Turbos, sport-cat downpipes, ECU, TCU and CPC |
| TTE760+ turbos | 98 RON | 780 hp proven | — | 850+ hp on higher octane; tune required |
| RENNtech Stage I / Stage II | 93 US | 709 / 767 hp | 638 / 633 lb-ft | 610 / 660 whp; fuel system included |
| Weistec W.3 | — | 820 hp | 720 lb-ft | Rebuilt stock turbos with billet wheels |
| Pure900 | — | "800+ WHP Capable" | — | A hardware rating; custom tune required |
Parts list
- Upgraded turbos required
TTE760+Weistec W.3Pure900RENNtech Stage I
Weistec lists its tune, TCU tune, CPC, downpipes, plugs and water-methanol as required with the W.3.
- High-pressure fuel pumps required
RENNtech HPFP upgrade
RENNtech claims 37% more flow.
- Gearbox software or rebuild required
Weistec TCU tuneWeistec 7-speed MCT build (2015–18)
Weistec's clutch-pack build is made to "withstand far greater levels of torque than the factory transmission".
Big turbos and forged internals
830–950 hpStage 4 means complete replacement turbos and, for the biggest figures, forged internals. Weistec's W.4 claims 950 hp and recommends forged rods and pistons; Posaidon's RS830 fits pistons and rods and claims 830 PS, and its RS830+ 880 PS.
Parts list
- Replacement turbos required
Weistec W.4Pure1000Posaidon RS830
Weistec: "Stock downpipes will significantly limit power gains".
- Forged rods and pistons for the top figures
Weistec forged rods and pistons
Weistec says its pistons need sleeved iron bores and an experienced builder.
Watch: real builds
From tuners', shops' and motoring journalists' own YouTube channels. Nothing loads from YouTube until you press play.
Questions to ask the shop
- Is my car pre- or post-facelift, with the 7-speed or 9-speed gearbox, and will you tune the CPC module as well as the engine?
- Can you flash it through the diagnostic port, or does the computer need to come out? Can you put the stock file back?
- Does my car have a particulate filter, and which downpipes and exhausts actually fit it?
- Is the file written for 98 RON, and what knock and air-temperature margins does it leave for a hot summer?
- What gearbox calibration will you use, and at what torque do you recommend a clutch-pack build?
- Will the car pass the annual inspection with its catalysts and no fault codes, and do you give a written warranty on the engine and gearbox?