Most newer bikes tend to be jetted a bit lean out of the box... so even a stock bike could benefit from a step up on the main.

 

Those loud pipes will get our riding areas shut down quicker than anything else. The stock exhaust on a WR isn't a bad exhaust once you take the small baffle out of the big baffle. All you need to do is drill some rivets and it comes right out. Not supposed to make it a lot louder, but wakes up the power. Chances are if you're messing with a 450 you don't need anymore power. I'm 6' 205lbs. and my 450 is plenty. It has more power than I'll ever need and sometimes too much for my type of riding, but it is nice to have.

 

I do love the noise a 4 stroke makes with a straight thru pipe on it. Where i ride it doesnt matter about noise. My friend owns the place, 2 mountains for miles. I just use the bike for putting around the moutain to save on fuel and wear and tear on the trucks. I gotta find out what main jet i have and step it up, from what im hearing tho a 165 or 168 is what i should put in.

 

Ask some people in Southern California if it matter if you own the land or not. I remember reading not too long ago about a bill they were trying to pass and eventually passed. Jeremy McGrath himself showed up to try to fight it, but it passed as far as I know. Do a little research on sound regs and offroading you might be surprised. I ride in Washington and they are working on the same thing with I believe a 45dB sound limit on off road equipment.