They are all going to be louder than stock. I would think in terms of quietest to loudest it would be:Looking at these 3 axle backs. Which one is louder over stock? I've listened to a crap load of youtube videos but I can't tell.
I ran with Flowmaster ATs for the 1st year... they are definitely louder (and deeper) than stock, and a bit louder if you have a CAI.. but not obnoxiously loud. Just swapped these out for MAC Boomtubes (wanted more volume)... here's my thread and video clips of the Boomtubes. If you decide on Flows (Kit #17410), I've got a brand new set still in it's factory packaging. PM me if interested.I think I'm going to go with the Flowmaster for a little louder sound than the GTA's.