You need to put more consideration into the long run here. Even if you could get enough power to beat a yfz in a drag race, you'd still get completely annhilated when cornering, suspension, or anything else like that comes into play. A 350 modded that hard to even come close to a yfz would not be a trail friendly machine anymore, it would be unreliable and difficult to control. I'm speaking from experience here, when I say that "it's never fast enough". As soon as you make it faster, you will want to make it handle better, and soak up the bumps better so that you can use the new power. Then you can finally get the power to the ground, so then you'll want even more power. Eventually you'll have $5,000 sunk into a machine that was only worth $4,000 to begin with, and probably end up trading it in on a faster bike anyways because it still can't compete with a stock 450. Then, instead of taking a loss of $1,500 or whatever the depreciation on a stock one is, you will lose over $5,000 with all the mods you put on it, plus the depreciation. Don't be stupid.