ive got an 07 400ex, almost 12 hrs on it, gonna get a K&N air filter for it, also want to get an exhaust system for it. what is the best performance exhaust there is for a stock 400ex, regardless of sound? what in yalls opinion is the best sounding exhaust? thanks for the help guys!

 

First a bit of advice....don't run a K&N! I can tell you from first hand experience that they pass dirt!!! Get the ProDesign (ProFlow) adapter and foam filter (made by UNI). These flow plenty of air and will give you way better protection! http://www.prodesignracing.com/pro_flow_kits.htm

Also, you will not get the most out of your exhaust if you don't also open up the airbox. Here, I highly recommend the EHS Racing airbox lid with Outerwears. The Outerwears gets the worst of the dirt, yet flows lots of extra air. http://www.ehsracing.com/index.htm

If I were doing my 400 today, I would go with the FMF PowerBomb, and the Q4 muffler. http://www.fmfracing.com/default_det...X400EX&cat=125

And of course, I assume you know that with any air intake and exhaust mods, you will require are rejet!

 

alright, thanks, ill get a uni filter and that box lid at some point. still havent decided what exhaust to get... i know that jetting will need to be done, but i know almost nothing about it. i know the basics of carburation, but this is my first sport quad and the first atv that ive tried to get some power improvements. cud u enlighten me a little bit?

 

and another thing, i ride in REAL dusty sand in central florida. after a cuple months of just weekend riding, my recon's air filter was coated in sludge.

 

and i checked out that ehs airbox lid, and if i did that then would i block off the airbox intake to keep the dirt from getting in through there?

 

I ride the southwest desert, and believe me I know what dust is!!! I run the EHS lid, and left the stock snorkle as is.

I have three air filters for each quad. One is in the airbox, one in the wash, and one oiled up and ready to go when I need a fresh one. I can always get through a long weekend of riding without needing to change the filter.

As for a rejet, don't do your mods one at a time or you will be rejetting over and over. Collect all the parts, and then install them all at once and do the rejet. Jetting is more art than science, and unless you want to spend lots of time learning it (seems kind of silly in the age of fuel injection!), just pay to have it done by an experienced professional.

 

well i would like to learn about it, im just 16 but plan on keeping riding atvs as a life long hobby. what about these dynojet kits?

 

everything recon says is true except the Q4 muffler wont give you the best power plus their over 300.00 bucks.i had the Q series on my warrior and i didnt even have to rejet that should tell ya something.also on my warrior the Q series stuck out past the rear grab bar it was too looong. never seen 1 on a ex.i have a hmf on my 07 400ex looks good power is good just a bit loud for my taste!and i have the dynojet kit they give you a adjustable needle too, but put it in the stock setting, it beats running to the dealer for different jets all the time

 

ya, ive heard good things about the pro circuit t4 exhaust, so prob either that or the big gun. but about the dynojet kits, do they just give u the needles and stuff and u put the certain ones in for the amount of mods like airbox and exhaust? and if you know what ure doing, how long does it usually take to change the jetting? i havent done any jetting but i want to learn and it doesnt seem that hard, im really good with putting things back together and all.

 

I've heard good things about the T4 too, and also check out Yoshi pipes

and I agree with recon, get a foam filter, and IMO it's alot cheaper just to buy individual jets at 2 or 3 dollars, it's alot cheaper than the jet kit