Excellent Thread. I did tons of research on this before "pulling the trigger." In a nushell, I went with the FRPP M-5230-GTAs.!
There are two FRPP axle-backs.... FRPP M-5230-GTAs and M-5230-5GTs. The GTAs are "zero drone," slightly louder at idle and sound terrific when you get on them - trust me. (They are cheaper,
www.ninosport.com to order) than the -5GTs. There is no doubt (as I've stood next to both, driven with others that had both, etc.) that the -5GTs (a.k.a. Borla Stingers/same thing as FRPP) are.... A) Louder and B) drone around 1500-1900rpm - which for in-town driving---not for me.
Sound is subjective..... One person's loud is another person's obnoxious and another person's not loud enough! LOL. However, there is no doubt the 5GTs are louder than the GTAs, but the GTAs have "zero" drone and cheaper - and the 4" tips look awesome. Heh, the GTAs are OEM for the Shelby GT and Shelby GT-H. If they are good enough for Shelby -- good enough for me. (Can you tell I like the GTAs--you're right. They are actually "seasoning" and getting a little louder-- My advice, check youtube.com, but more importantly find someone that has each and go for a ride with them like I did.......
Oh, almost forgot. The GTA is more of a chambered exhaust (no hp increase) and the 5GT is more of a "straight-through" design ...slight hp increase (allegedly 1-2 hp)....I wouldn't expect any more than this.......
Here's a nice decision ender for you.... Open this link, stock CS/GT on the right, GTAs on the lett....end of story....
http://forums.bradbarnett.net/attachment.php?attachmentid=24044&d=1176584664