So a few weeks ago my engine had been misfiring, so I brought it in (2007 rx8, 85000km, still under warranty) and the dealer replaced plugs/coils/wires. The engine stopped misfiring, but it still doesn't sound right. The power is not there especially at higher rpm's, and it sounds a lot louder then it used to. It sputters somewhat in higher rpm's, especially in third/fourth gear.

I'm not a mechanic but to me it sounds like some issue in the exhaust system. A friend lent me his ODBII reader so I was gonna check it out, but I was wondering if anyone could give me a heads up on what to watch for?

 

check your cat converter.

 

Sounds like your Catalytic Converter is clogged.

 

Sounds like you posted a technical question in a general discussion forum

 

+1 on your cat. Anyway, bring it back to the dealer and have them check it out. It's still should be under warranty and you don't have to worry about costs.

 

Alright sounds like we have consensus . Thanks for the help.