I registed 81dB on my mk3 running CAT, and Milltek stainless steel 2 box system at 4.5k rpm. Mates mk2 gti 8v running Jetex 3 box, registered 97dB at unknown revs cos his rev counter was broken, est 5k rpm.
yes mine is one of the group-N doo-dahs. sounds great on idle and when you get going it seems not so loud....lol. my car is also fully stripped out.
mine seems to peak at 3.5krpm (noise wise) and then go quiet after 5k, but ive only got 1 silencer. does your OMP have 3 silencers also?
