um, I don't know..I still think it's one of those 'all show and no go' type of mods. I'm sure some ppl appreciate it, but I'm just not into the 'car show' scene (a bunch of weirdos imo). Dual exhausts just adds extra wieght, and makes you look like a riceboy. I don't know if other aspects of performance would be effected though. I just think it would be slightly more tasteful to invest in stuff that make you go fast, than stuff that merely gives other ppl the impression that you're fast.
On a side note, I guess even some OEM manunfacturers do the same silly thing. Check out the dual exhaust on the S2000, or the Audi TT ( which uses the 225hp version of the VW 1.8t 4-banger)