i was looking for simple bolt on performance parts for my 1999 Trx400ex, is the big gun box worth it?

 

Stock, no, wont really do much. But if you open up the air box, or run with no lid, rejet, and add a pipe, you almost need a performance cdi, Honda has the lowest set rev limit of any quad ive owned, i have both a 300 and 400ex, and after freeing up both intake and exhaust, they actually ran worse than before, they revved nice and quick, but hit the rev limit so fast, they started to sputter and were slower, because you had to take it easy on acceleration and watch your shift points, to keep out of the limiter. I bought a White Bros. +1000 rpm cdi for both, day and night difference, now you can power shift at full rpms, and get every bit of power out of the freer breathing engines. If you are just adding one to a stock engine with no intake or exhaust mods, you wont see any improvement, unless you have dropped rear tire size or regeared lower, and need the extra rpms to keep out of the rev limiter.

 

thanks, for replying, and no im not running stock, i got k&n intake, fmf powerbomb with power core 4 and moose stage 1 jets

 

Then if this box adds +1000rpms to the top end, then I would have to say, yes, it would probably add to your performance package.