^because i said so. a newb giving advice to another newb. lol. no, it's because he's planning to keep his spt catback (2.5in flange???) and vandde and i figured the perrin 2.5 taper would be best??? and i know he doesn't have to 2.5 taper but best to??? please give us your thoughts nuke. Edit: just checked and perrin doesn't taper.