Re: X-Pipe or stay with the Y-Pipe?
You won't really gain much in performance, maybe 1-3hp, idk if it'll even see a gain at the rear wheels. Definitely nothing you'd feel.
As for sound.. I'm not sure; I haven't had the pleasure of hearing many aftermarket exhaust vs. stock exhaust or anything on V6s. I'd suggest using YouTube.
2016 Comp Orange GT (current)
Aurora - 2002 Boosted GT! (Sold, sadly)