t6 will work of w/ porting, but def go t5 or cpi if you getting into big bore draggers (or get drag pipes ). Trinitys deal is hard to beat right now, I have FMF q-series right now, they have no top-end, when I bought the bike it had them, changing to T5, because have more mods then stock. Had T5s back in 1989 on my 89 shee and they ripped, also bought a banshee couple years ago and they had them.