Most power out of 09 yz450f

I just got a brand new yz450f and I am wandering what aftermarket parts will give my yz more power? Also how much more power would a mega bomb and factory 4.1 exhaust give my bike.

I just got a brand new yz450f and I am wandering what aftermarket parts will give my yz more power? Also how much more power would a mega bomb and factory 4.1 exhaust give my bike.

Not very much more, if any. BB kits and head mods is where all the power is at.

Proper jetting, DRD exhaust (much better and cheaper than the FMF), 06 exhaust cam

The stock silencer on the 08-09 YZ450F is terrible. Pretty much any aftermarket silencer (or a stock 07 silencer) will show pretty good gains in the bottom to mid range, some better than others. The FMF system is one of the better performing systems, as is the Dr. D system. Head mods will offer pretty good gains as well.

For MORE power you will need some of the expensive mods.

For more power in the low to mid without giving up your top end Justin89 is right and he should know cause he has tons of mods to his bike.

Is there a way to modify the stock silencer and open it up and get the same result as buying a new FMF slip on?

Is there a way to modify the stock silencer and open it up and get the same result as buying a new FMF slip on?
A couple of people have tried it, and they ended up with a very loud bike that didn't perform as well as one with a decent system on it.

Thanks for replying grayracer.

I was hoping I could just modify my stock silencer but it sounds like I'd be wasting my time. Looks like I'll have to spend $300 to get an FMF unit and give the my stock 08 YZ450F power the stock silencer is robbing from the engine.

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