The factory exhaust(s) are all one piece, fully-welded designs. At the factory, they install it BEFORE the subframes, so there is nothing in the way at that point in assembly.
The aftermarket exhausts are all 2- or 3-piece bolt-together designs, so they can be installed with the factory subframes still in place.
I'm personally a Borla fanboy, but every part I've gotten from FS/FSWerks has been amazing quality. I'd have zero apprehension about trying their exhaust.
2003 CD Silver SVT Sunroof and Machs
#1229 of 3985 Date of Birth April 21, 2003
Borla Cat-Back/SVTF tip, Steeda Short Throw,FRPP 9mm Plug Wires, Upgraded "Big 3", HIA Short Ram, Xcal2 tuned by FocusSport, SRF TB, EAP Wheels(thanks John), Audiophile sub(thanks John), Euro Grill(thanks Aaron)