Originally Posted by F.I. Inc.

You cannot go wrong either way. By adding our exhaust to your Z, you will add depth and volume to the exhaust. In addition, there is absolutely no rasp at all. What the 18's will do over the 12's is just make the interior sound slightly quieter. At the end of the day though I feel it will not be too loud for you if you choose to go with the 12's and stay with the stock cats. Pleas do not hesitate to ask if you have nay further questions...

Thank you, Tony
Fast Intentions Inc.
(818) 882-2788