This is a much discussed topic here, and if you like, search for which exhaust should I buy or something like that and you'll find all kinds of stuff... But, since you asked, it's all in what you want... how do you want it to look/sound/perform? Slip on or full system? Low/High mount? I have a low mount carbon fiber evo single port on my 04 Liquid Silver(the fast one) R6, and I couldn't be happier...