The S65 based M3 is a very popular car for tuning, We see a lot of these in after having primary decat. We are able to disable cold start, remove decat cel light & remove the speed limiter and for those wanting extra such as burbles we are happy to provide. Cars coming into us with the cat already removed will see 25-30bhp gains and the decat will free up another 10bhp on its own. Despite claiming 420bhp these cars can vary massively on the stock figures they produce with us usually seeing between 360-400bhp stock. A stage 2 remap combined with a Gts Dct gearbox flash can really wake these cars up. Like all petrol cars we tune we recommend shell v power or tesco momentum but it is especially important on this engine due to being naturally aspirated and high power.