Raspy exhaust leak type noise but no leak?

I'm not 100% sure, but catted probably doesn't have that hissing sound.
 
There are plenty of threads on different forum on this topic. :hiding:
 
I got a question do you think using A 2.5 in bell mouth gasket on a 3in downpipe can create a loss? Feels stronger but forgot to swap the gaskets out
 
I just installed my FR downpipe yesterday, stock exhaust, and mine makes a hissing sound also under acceleration. I have yet to check it out. I am catted and about to start tuning with Vit. I wonder if the flex piece leaks a little?
 
I just installed my FR downpipe yesterday, stock exhaust, and mine makes a hissing sound also under acceleration. I have yet to check it out. I am catted and about to start tuning with Vit. I wonder if the flex piece leaks a little?

You are hearing rasp because it is not properly tuned.
 
Rasp is not caused by a leak. It has to due with frequencies going through the exhaust system...which is going to be influenced by how the fuel is burnt and exhaust gasses are coming into the downpipe. Hence, you need a tune.
 
Have you been tuned by vit after installing you DP @squiggy ? i'm at cal 1.5 and it's still making and hissing sound under acceleration (catted dp).

Yeah. I ran a catted Full-Race DP with just the ReFlash and it sounded like garbage and ran even worse. You have barely gotten started on tuning. It is going to take 30-40 tunes to be finished.
 
Yeah. I ran a catted Full-Race DP with just the ReFlash and it sounded like garbage and ran even worse. You have barely gotten started on tuning. It is going to take 30-40 tunes to be finished.

Glad to hear that the hissing will be mostly gone by the end of the tune, this sound is not particularly pleasing.
 
The hissing will not go away, it really doesn't have to do anything with the tune. I was fully tuned by Vit with my 2012 si and I had a full race catted dp and I had the hiss its just the way the it sounds with k24z7 integrated header.. After you're fully tuned you'll think it's gone because you'll be hitting WOT a lot lol
 
The hissing will not go away, it really doesn't have to do anything with the tune. I was fully tuned by Vit with my 2012 si and I had a full race catted dp and I had the hiss its just the way the it sounds with k24z7 integrated header.. After you're fully tuned you'll think it's gone because you'll be hitting WOT a lot lol

It is mostly gone and not really noticeable even under normal driving. And, yes, it does have to do greatly with the tune. Rasp is a frequency issue. The way the fuel escapes (and resonates) into the DP is going to be dependent on how it burns/ignites.

@323 do you notice rasp with your DP?
 
I have the Full race exhaust and catted D.P, no tune and stock airbox. I am not experiencing any hissing or leak sounds. I believe there was a thread where the guy couldn't find the leak and it ended up being cracked at the head of downpipe. Did you check the D.P at the block?
 
I have the Full race exhaust and catted D.P, no tune and stock airbox. I am not experiencing any hissing or leak sounds. I believe there was a thread where the guy couldn't find the leak and it ended up being cracked at the head of downpipe. Did you check the D.P at the block?

Air box isn't going to make a difference, but you really shouldn't be running that DP without a tune.
 
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