Hands down go with the white bros it is a big gain over stock and do get the header i ran a 400 and stayed right beside him after and got smoked before

 

I have a WhiteBrothers R4 on my 400ex and it is great. best ;ow end tourqe you can get I don't know much about the E-series. All the Pro riders sponserd by WhiteBrothers run the R4 it's the best bang for your buck. I wouldn't go run out and get a head pipe yet. I would get a WhiteBrothers stage1 cam first. I'am not sure how big your bore is but I think you said it had a small kit on it and putting a big head pipe with a nearly stock bore on a 4stroke is not gonna do you any good. Wait until you get a cam and then mabey get a head pipe or bump your bore up a little more. If i wee you I would just jethott or send your stock pipe to LRD and get it ceramic coated for $80.00. This will make your 300ex run smoother and about 50% cooler which will help with the ponies. GOOD LUCK

 

can anyone tell me where i should start to get more power out of my 300?

 

 

i have heard the curtis sparks pipe is awsome.im buyint one after christmas.whatever you do dont get a supertrapp or cobra(i know from experiance) they suck

 

Hey it all depends on how much money you are working with if its not too much get a k&N filter if you got some put away get a WhiteBrothers pipe then you can go from there

 

 

can i put my own pipes and jets in easily?