I have the Invidia N1 street catback which has the resonator in, but I have the invidia V2 catless down pipe, the resonator makes it deeper and more rumbly, but no resonator makes it really raspy, either way it will be very loud and you won't be disappointed with it! Not sure if having no cat is the reason mine shoots blue flames? I know having a bov makes it run rich for that second it vents is this the reason?