What upgrades could i get for a stock 04 300ex to get a little more go out of it and would it compete in a straight shot against my warrior

 

There is hop-up potential in that engine! You can do the usual stuff, like increase the air intake and exhaust. I never do anything beyond that, because once you tear into an engine (high compression piston and the like), you will risk compromising reliability. That engine will run forever if properly cared for.....

The stock header is pathetically small. I put an FMF PowerCore4 muffler on mine, and it came with a larger header. An EHS racing airbox lid with Outerwears, and a UNI foam air filter (and of course a rejet), and I think you will notice the difference.

The stock tires are lame, and should be replaced anyway. If you go down to 20" in the back, you will lower your effective gearing, and gain more low end power (quicker off the line). But, you will lose 1" of ground clearance and a little speed on the top end. If you want more top end, then just do some gearing changes.