what is the best 4-stroke pipe?
1)supertrapp
2)fmf
3)pro circuit
4)yoshimira
5)cobra
6)DG

 

You forgot White Brothers. I would say 2,3,4 or the WB.

 

NEVER buy a Cobra or DG unless u are on welfare. White Brother, Yoshimura, and DMC make EXCELLANT systems, the best you can buy! Get a full system too, not a slip-on.

 

YOU FORGOT ABOUT THE LRD, I HAVE ONE ON MY EX MY FREIND USED UNTIL SOME ONE CRASHED INTO HIS REAR(ME,,,HAHA)NOW HE HAS A WB AND MY QUAD IS MUCH FASTER THEN HIS....LOOK INTO IT!

QUAD040

 

Out of your list the Yoshi would be the best. It has a great design and a good history. But there is another company that you should look into which is called GT THunder! THere site is http://www.gthunder.com and they have alot of cool information and awesome products that they hand make. Check them out before you make your purchase. THey also have a lot of dyno specs on different pipes and what not.-
Eddie

 

It depends what kind of riding you do
racing-yoshi or dmc, maybe wb
woods-fmf or supertrapp( I still want to know which one of these gives more power,mega max or ids2)
I don't know about pro circit.
stay away from dg-they are not a good quality pipe
cobra is cheap too(quality and price)