Annoying Rasp - Gasket Related?
 

I recently installed an Agency Power Midpipe and Greddy SP2 exhaust. Inbetween 4,000 and 5,000 RPMs, I hear this gross raspy sound. I've heard that it's somewhat normal with midpipes, or maybe just the Agency Power specifically, but here's the thing:

The rasp is more than twice as quiet/subtle when the car is fully warmed up. When has just been started, the rasp is REALLY raspy and crazy annoying. I told one of my friends about it and he thinks that it may have something to do with the gaskets, saying that I may have a leak, but that under heat, these gaskets expand and essentially stop that leak once the car is warmed up, making the rasp quiet down/go away.

For the record, I reused the header-to-cat gasket, and bought new gaskets for the cat-to-mufflerpipe and mufflerpipe-to-exhaust. I tightened the shit out of everything when I installed it, but what my friend says about there being a leak sounds like it makes sense. Just wanted to know if you guys have any other ideas, or if this might be the problem?

Also, if anyone else is running this setup let me know if you do or do not have this issue.

I'm running the agency power and greddy se and get the same rasp around those rpms. Really annoying. I've replaced both gaskets and it didn't help

Bumping this thread because this is still annoying. Thought I'd add in something that I've noticed:

First start of the morning/engine completely cold: Sounds like complete shit around 3.5k - 4.5k RPM
Engine is technically "warmed up: Sounds much better; annoying rasp is 80% gone
Hot engine (During or after hard driving): Sounds beautiful with little to no rasp

Any ideas? I seriously doubt that engine temperature has this large of an influence over the sound of my exhaust.

i heard the rb mid doesnt have much of a rasp.... i have my ap mid paired witha hi power and after the engine fully warms up most of the rasp is gone.... just try not to rev to high when the engine is warming up and it wont bother you much.. its what i do....

Have an exoticspeed mid, and i get the exact same thing you're talking about.... does your mid sit lower than your stock did by chance?

get a thicker header to cat gasket from race roots for example

jack the car up start it then get underneath and feel around all the flanges for where there might be a leak

Was thinking of buying some of the high quality crush gaskets from Race Roots. Only thing holding me back is that they're like $45 and I'll be pretty pissed if nothing changes. Might end up trying it, though.

To tell you the truth I haven't felt around for leaks because I was so sure I tightened everything as much as I could. I should check.

Also it's a shame to see so many others having the same issue. It's definitely specific to the midpipe because I watched a video of a guy with my same exhaust, but with a BHR midpipe, and there was not even the slightest amount of rasp. I really wish I knew what causes this.

Let me try to help. I'm pretty sure it's a leak in one of the gaskets. I'm going to install a used OEM catalytic converter that I bought. I had a muffler shop loosen the bolts for me (they can't install the cat for me because federal law prohibits a shop from installing a used cat). Because it's been raining nonstop for the last 3 days, I haven't been able to swap the cat. Therefore, I've been driving around for the last 2.5 days with loosened bolts and thus a leak in my exhaust.

And I've experienced exactly what you have. When the car starts up it is so damn loud, raspy, and annoying (not too mention a heavy fuel smell that gives me a headache). When the car warms up, the noise disappears and goes back to virtually like the way it used to be. Like you said, presumably the heat expands the gasket.

So I'm pretty sure you need to get new gaskets, at the least the one between the header and midpipe.

I had the same problem - it was due to a hairline crack in my aftermarket exahust. When the metal heats up it expands and the crack/rattle gets suppressed.

Check your exhaust tips for cracks.