Here is what I did leading up to when the noise appeared. I took off the hi flow cat and put the stock cat back on for emissions test, after the test put the hi flow back on, that's it.

Now when I accelerate there is a fairly high pitch sound, not a whistle but more like a siren. It seems to coincide with boost build up. This wasn't there befor.

Another thing I noticed is that the ss exhaust manifold has a faint glow after a short drive (the turbo does not glow). Is this typical for a ss manifold? The car feels ok, boost up to the correct setting no problems. Functionally everything seems to be ok.

Anyone have any ideas what can cause the noise to appear and does it present a problem for the car? Thanks.

 

Bump.

I just installed an Efini Y-Pipe and began hearing the same sound. Hopefully this is a common problem that someone can chime in on?

Thanks,
Jesse

 

It is probably just a weird exhaust leak. Check for black runs on the pipes, where you bolted them up.

 

Why did you have to remove your hi flow cat. You couln't pass emissions without it?

 

Check the hoses leading to the intercoller. Sounds like a it make be a leak there. I have the y-pipe installed and no strange sounds. I don't recall any real changes after installing it.