Hey there everyone!

Just recently purchased my first c5. 53k, manual, here is my issue.

In higher gear acceleration (4th,5th,6th) I hear what sounds like an exhaust leak from drivers side under hood. I run 93, changed oil when I got it using 5w30 Mobil 1 and wix xp filter, I have checked plugs and none loose, all bolts were in tact and secure, however I did go ahead and replace the donut gasket, manifold gasket with oem mls. Even used new hardware and torqued to spec with the updated tsb. Sound is a little quieter but still obvious. It does not sound like a lifter as it’s not really a tick when idling or rev in neutral. It’s not the piston slap I get while warming up. It sounds exactly like an exhaust leak and will get louder the more I press the gas in the higher gears only is when I hear it. It may do it in lower gears but with the exhaust set up I just can’t hear it but it definitely is not noticeable in 1st or second or reverse or idle. I’m loosing my mind trying to figure it out. I wonder if it’s a hairline crack in the manifold welds or manifold itself?? All surfaces were cleaned throughly before new gaskets were installed including air injection port. Anyone have any issues with this? I plan on doing header kit from either Kooks or American Racing in the winter with some other stuff. Just curious if anyone else has this issue? Any help is appreciated

 

Moved to C5 Tech for assistance.

 

I'd imagine, a cracked driver's side exhaust manifold (check under the heat shield welds), or possibly a fractured AIR pipe tube. If that's it, some long tube headers might be a great (needed) mod.

 

Btw, congrats on your first C5! Welcome aboard!