Hi, thought Id post this for info for any track day plans: most track days restrict noise to 100-105 dBA measured 0.5m from the car at 2 thirds of max revs. Some also do drive past measurements obviously further away for induction noise etc. On some "quiet day" events like goodwood, limit can be as low as 95 dB and Ive come across maniacs imposing an 85 dB rule.
So, enough theory, I measured noise levels on my car with cat back (silenced) k-tec exhaust and BMC with lower front grille intake, and Im well happy with the results - spot on - without the mid silencer, I would have been above regs:
50 cm from exhaust at 5 - 5.5k rpm was 94 dBA . Same but when bouncing off the limiter (...) 106 dBA. Front induction at full throttle was 104 dBA with noise level meter right in front of induction hose.
So the car is spot on noise regulations. Anybody with a straight cat back and no silencer, check before attending a track day or you may be turned back.
ohh, if youre a bit "just", an old trick is to reverse the car against a nice grassy (ideally tallish) patch. Will absorb the odd dB
