I have a 2005 G sedan with it REV engine (I believe its the same engine as the 350z's), a Z tube intake, kinetic high flow cats, and a stillen exhaust. I heard some louder exhaust noise a couple months ago and tracked down the leak. The junctions on both sides directly under the driver and passenger seat were leaking. I use some cheap gaskets from the autoparts stores that were open for that day. Got them all sealed up and ordered some vibrant gaskets from coz. I was hoping that the cheapies would never give out, but wasnt getting my hopes up. As suspected those guys blew out. So I replaced them with the new nice ones... and we still have leaks. I took them off cleaned up the surfaces and tried to line the pipes up perfectly. STILL a leak. Any ideas?

I was thinking maybe there are some back pressure issues, but I dont think thats a real common problem to have.

Thanks in advance everyone!

 

Tighten all the bolts?

 

They are tighter than a nat's a** wrapped around a whine barrel!

 

Stick some SeaFoam in and look under the exhaust to see where the smoke comes out from. That's what I did to find out where my leaks were.

 

Problem is the flanges on the CATS, exhaust, or both aren't perfectly flat. You can try using the red RTV with the gaskets in order to perfectly fill the gap and steal it up. Another option is to find a multilayer metal gasket to use, better than those coated gaskets that you got from Vibrant. Something along the lines of this product: http://www.grimmspeed.com/grimmspeed...25-2-5-gasket/ The multilayers tend to do a better job of forming to flange surface imperfections.

 

Have you ever used these? They are kind of pricey, but completely worth it if they are solid.

 

They are tight, but are they at the right spec?

 

~26 ft-lb

 

Hhhmmm

 

Could try using two gaskets a joint

 

Wouldn't that create more possible leak points?

 

It could. But would compensate for a bigger flange mismatch