General exhaust discussion & questions
By T.EG6
#347426 Hey im trying to get rid of rasp/drone which comes on when around 4000 rpm.

i have a b20 vtec with dc headers 4-1,high flow cat, magnaflow resonator, and greddy evo2 muffler. The pipes are 2.25"

the car sound great very deep aggressive sound but when i punch it at around 4 grand i hear reasp and same with if im decelerating from higher rpms to 4 grand.

I wonder if there is any way of get rid the rasp?

I hear adding another resonator could help or heat warping the pipes !!??

Any help is appreciated thanks.
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By Leppy
#347427 You're setup sounds great, I don't see why it would have a rasp personally.

One thing I would check is to make sure you don't have any exhaust leaks or loose bolts or heat sheilds. I had a rasp for a while that turned out to be a loose cat heat shield rattling under the right resonance frequency, which was around 2500-3000 both revving and back-revving. Once I got that settled the 'rasp' sound went away entirely.
By T.EG6
#347428 Thanks yeah thought it was a good setup, my exhaust shop just installed my greddy and they checked everything for me so I know for sure there is no leaks and my heat shield is Def not lose... the Rasp/drone only comes on at 4grand and it definitely doesn't sound like a heat shild rattling about...

Called my shop and they said it's because it's a stright trough exhoust all the way from he'd to muffler and they suggested me adding another small resonator to get rid of it...

I also herd wrapping the mid pipe would take care of the rasp but I'm not sure about that...
By T.EG6
#347435 No it is not a test pipe, it's a magnaflow high flow cat.
By T.EG6
#347438 The cat is only like 2 years old also the resonator is a 18" magnaflow. My exhaust shop told me I should maybe put another resonator in somewhere if I don't like the rasp that coming on at around 3-4 rpm... but I'm not sure about that... like I said the system sounds great I don't want to ruin or quit down the sound of my muffler, would another resonator quit down my exhaust sound or would it just take the rasp out ?