I have a 99 A4 2.8 which i had custom exhaust installed at a local shop. at first i only did a system from the middle silencer muffler to the rear exit muffler. i put a straight shot performance magnaflow muffler out the rear. at first this was nice because it was not to loud. but at higher RPM it made a nasty rattling sound from the back. i thought it could have been stopped up air from the big middle silencer causing the rattle, so today i had the middle silencer pulled off and replaced with a straight pipe. this gave the car a nice deep tone, (a little loud for my taste), but not so integra sounding. but that tin can sound at about 3 thousand RPM did not go away, it got worse! Any idea's?? im out of ideas? it only sounds nasty when i hit about 3 thousand RPM. could it be my rear exit muffler? is there anything to get rid of the nasty integra sound at higher RPM?