Hi, my uncle asked me to do some research for him on silencers for his 2004 Kawasaki KLX 300, because the stock one is a little less than pleasing. I found the FMF Power Core 4 for that bike, and also the Pro Circuit T4, both around the same price range. He is mostly a woods rider, but wants more of a power gain from his bike. He also wants to spend less than $400. Are those good silencers, or should I be looking for something different, Thanks.
i personally think that aftermarket (loud) exhausts are lame and a waste of money. if you want that bike to be more pleasing, make sure you have done the free mods first (see http://www.planetklx.com/ for more info). that makes a noticeable difference. then a pumper carb is a good bet. i became pretty happy with my 300 engine after putting in the pumper carb.
some guys have had the flywheel shaved down. the klx comes with a freakin' boat anchor for a flywheel, so that will perk up the response quite a bit without making it too stall-prone or anything.
eventually, you might want to think about a 330 kit. or a bigger bike.