So I talked to Billy Holt at WRH Racing and he told me to cut of the down-turn at the end of the pipe, then with a drillbit the size of the hole, drill out the baffle that is about 1 inch inside the pipe.

Question is, can I make the hole too big and screw up the performance? How do you determine what size gives you the Best output for that pipe/engine. I know that if I do what he told me to I will be fine. But I was thinking about drilling a 1/2 inch hole (get rid of the existing exhaust output ....little pipe) and then drill the same baffle that is about 1 inch in with a 1/2 hole too....THEN with a stainless steel exhaust pipe fitting create a new output pipe and jb weld it in place.


I know that with my friends VStar 650, we modified his exhaust this same way....and WOW! But can you go to far?

 

Yes you can go too far.The difference is the pred is a two stroke engine.A two stroke engine requires a little back pressure to help keep the unburned fuel from simply going out the exhaust.A properly tuned exhaust system will allow the engine to actually pull the unburned fuel back out of the exhaust and back into the cylinder for a much fuller charge and more power and better fuel economy.Too little backpressure can actually cause a two stroke to run too lean and burn up the piston.This is not nearly so critical on a 4 stroke engine as they have valves to stop the flow of the air/fuel mixture.I'd follow Billy's advice to the letter![img]i/expressions/face-icon-small-wink.gif[/img]