i have a civic with full exhaust from the header back... no cat just test pipe... i just put the header on with the test pipe and axle back... i get a rhaspy noise at 3k rpm... is it because i have the stock midpipe in instead of the larger diamiter midpipe in? or is it beacuase theres no cat... i left the stock midpipe in because of the factory resonator assuming that it would help with that...