Every time I go over an abrupt bump in the road or an expansion joint I hear a "clunk" sound come from the rear underneath the car. It's been doing this ever since I got my cats installed. Also, I noticed last night when I had my radio off that I could hear a hissing sound kind of like air escaping underneath the car. From what I can tell its located right under the passengers seat. I'm running the Borla right now so wouldn't seem likely that after I had my cats replaced the exhaust may not be fitting as tightly as before? It sounds like the exhaust is not securely attached to the car and is flopping up against the underside of the car over sudden bumps. I don't have any way lift the car to investigate it so I am looking for advice from people who have possibly come across this. What do you think is going on?

 

definatly check your flanges on the borla iver heard of them leaking becaseu of so many different peices and the clunking might be the cats hitting the heat sheild or somehting of that nature probably nothing to worry about but the hiss almost positve exhaust leak good luck

 

I dont know what to say, but I find it sort of normal now. I have the same problem, but it doesnt bother me as much anymore since I have gotten used to it. I live in Miami and the roads arent all that great. So it happens often.
Any other Borla owners experiecne this condition?

 

I bet the borla mid canister is hitting the rear brace. I have seen this a few times. That piece just needs to be rotated a bit as the ends are angled and can cause it to sit real close to the brace.

Just call and ask to bring the car in. It should be a quick fix.

 

Cool. I'll call Doug this week and try to set up an app.

 

The hissing sound could be an exhaust leak. The best way to tighten headers and an exhaust is to tighten them down to torq spec run the engine for about 30 minutes shut it off and retorq it again. Don't get on it until it's check in case you're running lean.