Factory NPP 2013 muffler system on my GS, seems louder than my 2009 system. I am very happy, not complaining! Anyone know if the 2013 GS system is any different than a 2009 system? It maybe just me, but my hearing is actually getting worse, so I shouldn't be hearing it louder! Thanks!

 

I'd think it should get quieter since '12+ models have 2 extra cats?

 

I know mine is different but my 08 was a coupe and my 11 is a Vert. Vert actually has less drone with the top up and windows closed with the NPP in open mode.

 

I've heard that the 2012 Z06's / ZR1's got an X-pipe from the factory. Maybe that filtered down to the GS in 2013???

 

hmm thats weird...i know that your car has an x pipe and your old car i think had an h pipe that year still. but it should be quieter i would think because you have 4 catalytic converters instead of 2. i have a '12 grand sport and it was noticeably quieter than an '11 gs that i test drove both with npp. so i fixed that by putting headers, x pipe and no cats on my car back to the npp catback =) haha sounds much better

 

Maybe it's your excitement that makes it louder!

 

My wife says " it is definitely louder", and she isn't complaining! Maybe the acoustics in a 2lt GS, opposed to the base 1lt, makes it appear louder? It could just be me! Was hoping someone in the Know could give definite information! Thanks all!

 

throw some headers on it and then see how much louder it is haha

 

my 2013 GS with NPP sounds the same as my 80 coupe, I hear no difference