I have an 03 400 ex. I have fitted it with a white bros. e series slip on (12 dics), k&n , ehs air box lid, and the proper jetting. I was wondering what would you guys go with next to make power. I don't plan on using nitrous or any fuel over 93 octane.
If you suggest engine mods, what combination would you run??
Thanks

 

maybe a cam, or a new piston

 

port and polish the head

 

440???

 

First thing I would do is put your K&N in the garbage and get a UNi filter or put the stock one back on.

I hate K&N'S they shorten the life of your vechile oil and outwear or not. I would never bye a bike with one on it thats for sure!

Think about them look at the filtration it is rediculous!!!

Serious
Worry about reliabilty, not a little extra power( UNI is probably pretty close and a way better filter) , unless you have money to throw away or you get free quads er somethin

Just a little FYI

Don't really care if anyone listens

Eric Winkworth