This is a post from a very trusted and knowledgeable guy one here... tuned tons of sleds and can guess a clutch set up for you with one sentence.
"I owned 4 piped 700,s & helped tune a lot of others. Here is my order of pipes I tried & my personnal rating of how I thought they performed.
1 Bender(Dynoport)/Power inc end dumps(tie)
2 Hauck/CPR
3 SLP
4 Power inc centre dumps
5 Aaens "
He's right... i had Aaens and got a set of Pi End Dumps... huge difference it actually surprised me. I just figured "pipes were pipes" i soon found out the difference when i put the End Dumps on, the power increase, even over the Aaens is very noticable, but they are very loud... luckily i got 1 of the few 3 into 1 quiet silencers made with the pipes.
Post on both 4 stroke and 2 stroke side for PI End Dumps or benders or whatever. I found my set on the 4 stroke side where people are no longer in need of their two stroke pipes.... They all have turbo's now, buggers. lol