Currently have CNT exhaust, and decided to go with FI exhaust with 18" resonators. Will be getting it in Feb some time. SStevens has one installed on his Z and the quality is top notch.
Difference between 12 and 18 is how loud you want to get. 12 is louder, 18 gets loud at wot.
Just like everyone else, just call Tony and he will answer all your questions, great guy.
GLW your purchase.
