I need to get some more power out of my warrior

[YamahaWarrior350]

I got a KN Filter. I want to get more power can anybody help me what to get.  My spending limit is $700.

[VelociRaptor350]

www.yfm350central.com

[raptor426]

my friend has a warrior, he put on the full Yoshimura comp. series exhaust with the power up kit, it increased the power alot.  He only paid just over $500 for the whole kit.  Look at it here http://www.magicracing.com/view_category.asp?cat=153