I have a '94 with a rebuilt engine that dyno's out at over 400 rwhp. JetHot long tube headers with 4" mufflex system. Problem is that when I let it sit and idle at a stop light or drive-through or whatever the exhaust fumes are very heavy. I don't know if I have a leak, although I can't hear one. Any ideas???? Not a hint at any smoke, just fumes!

 

I'm assuming you don't have a cat? It's perfectly normal to get some fumes without the cat burning it off, but you might be running rich. Does your back bumper have a black soot-like film above the exhaust tips?

Quit braggin'

 

No cat. I haven't noticed any black spot at the exhaust but it certainly smells like it's running rich. How do I adjust that??? Does it have to be done with a diagnostic? or compuer???