Neilwf

can anyone tell me why I am hearing buzzing when I run through the gears from the exhaust system. stops when I let up on the throttle. have kevlar mufflers

mikeyds

Well while your engine is making VTEC boomies it's pushing a lot of vibrating air out the exhaust; there's probably something in a muffler or the cat rattling around. I'd get under it and give the exhaust a couple whacks in different places with a rubber mallet to see if I hear anything shaking. Or they could just be crappy mufflers

slalom44

It could be one of your heat shields. On an OEM setup you have one under the cat and a few on the manifold. If the area around the connecting bolts gets rusted it can break, causing it to rattle. You could replace the heat shield, or you might be able to add a flat washer under the bolt head where it's broken as a temporary quick fix.

Car Analogy

When seeking source of any rattle, time honored technique is whack and listen. Whack likely suspects or even just random stuff, and see if it rattles.

Whack with hand, with rubber mallet, etc.

EffWun

Usually the cat headshield, if you have an exhaust that attaches via diff carrier bracket not much can be done about the rattle.

zeroptzero

lots of aftermarket exhausts get internal baffles that break inside the mufflers when welds fail/corrode. Heat shields and muffler baffles are prime suspects.

HawkeyeGeoff

Yeah my Invidia just has a rattle on low throttle / cold starts. I've basically accepted it as character of the car. Don't care, race car.