i have a 94 civic coupe b16 swap that came with a straight pipe w/ no namer 3 inch exhaust... couldnt stand how loud it was at low rpms so picked up a 2.5 custom piping w/ high flow cat w/ a stock si muffler...

all in all after installation, it sounded Great! right up until it hits about 3000 rpms... then it has this nasty raspy noise! even on freeways once i let off on the gas or i accelerate the nasty raspy noise kicks back in... only way i can avoid the noise is by keeping a constant speed on the freeway and the raspy noise seems to fade right up until i let off on the gas or i accelerate?

some of my friends seem to think the si muffler might have some of the walls cracked or broken hence the noise? and another recommended a resonator will eliminate the horrible noise? before spending more money to weld a resonator or pickup a new muffler... i wanted some input from you guys. thanks!

 

get a resonator, the longer, the more it will remove the raspy sound. i think i got either a 32 inch or 42 but i forgot. all i know is that suckers long but it took the raspy sound away and made the exhaust note sound sooo much better.

 

a 24" resonator will be just fine. with a stock muffler it will get rid of the rasp as well.

 

thanks for the great info! so not the stock muffler at fault! :D ...oh and anyone have any great places you purchased your resonator from? good prices? thanks!! :D oh and does it matter where i weld the resonator ? right after the cat? before the cat etc?

 

put it in the B pipe after the cat. Most I've seen tend to be halfway between the cat and the bend. I've heard that most of the domestic cheapy type straight mufflers sound good as resonators on Civics... like magnaflow, thrush, etc.

However, I'd also say to doublecheck your connections. If you have rasp on/off slight throttle inputs, it sounds possible to me that the engine torquing could be causing exhaust leaks at the joints. Make sure that they're all tight, and you have the gaskets... especially the donut behind the header.

That said, the resonator will still help. From everything I've heard, a Civic with no resonator is going to be raspy.