Here is the Problem:
About two months ago I noticed the exhaust note got higher (as in goofy pitch from the usual when accelerating) when the car was in 2nd gear in between 1,800 and 2,100 RPMS; this would only occur once in the morning. This was during winter, although the car was kept in the garage it was usually fairly cold in my garage so I figured it was something with the temperature. Now that it is quite warmer out I'm starting to worry about it. Not only is it occurring just in the morning I have noticed it happening about six times a day for the past few days. My Z is a 2005 model, just had its 30,000 mile check up at the dealer so all the oils/liquids were replaced about three weeks ago. Has anyone else had this happen? I'm thinking it might be something with the exhaust (mufflers?) and hoping its not engine related. Any ideas???

 

mods?

 

Just aftermarket rims and slotted rotors. But if this turns out to be an exhaust related issue then I guess that would be a great excuse to get a Borla dual exhaust.

 

Exhaust note will change due to atmospheric conditions. In fact the exhaust will “sound” different in Denver vs Baltimore. That's a fact.