Just got my Nismo Exhaust installed last Friday. The car has been parked in my garage ever since. Today I started the car it sounded good. The car still was cold. I started to drive it and it seemed not as loud as before. But when the car reached normal temps it sounded very aggresive again. Is this normal?

 

Yes.

 

hmm lol funny. the opposite thing happens to me. I start it and it sounds good and as im going it sounds pretty loud. but half an hour later as im driving, it doesnt sound as loud. Its probably just my ears getting used to it

 

Sound changes as the cats heat up. My exhaust sounds MEAN in the cool morning temps. Me likey...

 

There is also the cold run map that has less timing and more fuel which will help change the tone.

 

Cold start = quiet (w/ Tanabe Hyper Medallion)
After driving for 30+ min. = significantly louder, starts crackling as well if i rev.