Go to raptorforum.com and actually hear from people who have the raptor 700. After doing my own research this is what I have found from multiple forums. Others, feel free to add on more pipes, but please do your research and not just your own opinions. Try to include the criteria at the bottom into your reasoning.

1) Barker Duals - Most horsepower; however, goes outside of the frame
2) LTE Duals - Very nice looks, all around good gains despite the criticism of the low end torque, not as loud as some
3) CT - Most horspower out of a single pipe, extremely loud and some consider ugly
4) Trinity - Very good looking pipe and best header design, decent horspower, may whistle during decceleration
5) HMF - People who buy them are very happy with the result, dyno numbers show not as powerful as those listed above.
6) WB Aluminum Pro - good looking pipe, rated well by ATV magazines, not full potential of horsepower
7) Alba - some consider it a good pipe if not doing further mods, loud but good looking
8) Nmotion - new pipe to the ATV market, supposedly pretty good gains, and loud
9) Two Brothers - Very good looking pipe, especially for the SE models, may burn plastics if heat guard is not added them


Things to consider when buying a pipe (not in any specific order):
1) For what use?
2) How loud? Spark Arrestor?
3) More for looks or for horspower? or Both?
4) Slip-on or Full?
5) Price?
6) Originality of pipe?
7) Weight of pipe?
8) Will the pipe get in the way of duners whips?
9) Do the headers have heat shields?
10) Single or dual?

 

What about the exhaust from Curtis Sparks Racing? Not sure on what pipes to get. I am a dune rider; I want the power across the whole range. Are the gains from one pipe to the next minimal, does one even notice the difference?