i have a 5at with 68000 on the clock and sometimes, only sometimes, when i rev high i get a weird odor, it goes away quickly, what could this be

 

ass, gass, or grass?

but for real, any description of the weird odor might help.

 

I get same order (smells like exhaust) when i gun it. Have 2007 5at. Perhaps something to do with loosing the vacuum in the system from WOT? Not sure if it's less or more vacuum but mabye it's somehow affecting the intake of the fresh air - OR we have a leak in the exhaust that somehow enters the car?

Hopefully others have experienced same. I've only had my car for 2 months and it only does it when i punch it and like you said, it goes away quickly.

 

If it's a sulfur-like smell (like rotten eggs) it's from the cats getting hot and/or the gas you're using and isn't really anything to worry about. Unless it happens all the time.