What pipe would give my quad the most power increase?

HMF, Pro Circuit T-4, or SuperTrapp

 

Both HMF and pro-ciruit are good pipes much better than suppertrapp. If it was up to me I would go with HMF since they make great low end power, and get yourself a k&n filter while your at it.

 

I had a HMF Powercore IV on my 2005 Kodiak. The sound was great and really helped the low end torque. I also had a Twin Air filter, but I didn't put a jet kit on, it was rich enough. Each one is a little different. Have to recommend a HMF.

 

I love my HMF pipe!