98 GSX exhaust leak

[onealt]

Aloha fellow tuners!
I have had a possible exhaust leak since installing a straight 3 inch exhaust. I say possible because I have had it tested twice for leaks but they cannot find anything? One shop said it may be running too rich which is putting fumes into the car? Any advice would be helpful. I don’t really want to go back to a catback system if possible.
Thanks

 

[BLACK'98DSM]

Did you check all the welds to make there's no holes? Have you tried revving it up while somebody listens for a leak? How old is the gasket where it mates to the head?

 

[pauleyman]

Let's start with why you think there is a leak and where? What did you change? What is on it now?

 

[MattHDSM]

How old are the nuts that thread onto the O2 housing where it connects to the downpipe? They will eventually stop locking and could back out causing an exhaust leak. I just had that happen a few days ago, new nuts (MB059359) and my exhaust leak was sealed.