There are several of us good builders to choose from on here. You will have to pull your cylinders off and send them out to be ported. Porting ranges anywhere from $200.00 up for most places including us!!
The T5s would be my choice if your gonna port it.
Feel free to call us.........
OMG ..... LOL That is some funny shit! Not funny that it blew up (sorry bout that ) but funny passing the guy and then him givin you a ride. How Embarrasing!!!
I can promise you they respond quite nicely to our porting ! Very good dune/ play pipe !!
To answer the original question, they pull good all the way through from bottom to top! They make much more bottom than say Shearers or Cpi 's but not as much top !
.040 over bore will not give him that much more power. If he went .080 or .100 over he might a "slight" advantage but not that much! It must be something else that is keeping him ahead like weight , gearing, jetting, moto condition, rider, etc....
Could be an air leak , waterpump impeller gone bad, ports not champhered correctly, etc... If you have any pics we might be able to help you more. I ran my drag bike .100 over for over 2 years with NO troubles.. Give me a holler if i can help you on your problem!
Paul Turner Mid pipes are very good for bottom and mid but not a great top end revving pipe for racing!!! About the best woods pipe you can find! I say if they are cheap and he can afford them go for it . He can always upgrade later ....
SSTs work great with dune/play port! If ya need more top end without sacrifising much bottom end try some 35pwk Air Strykers!! Give me a holler when your ready for them....