This spring im looking into up grading my exhaust system om my 05 400ex. i plan on adding a k&N filtered lid (home made, MUCH CHEAPER) and installing a header back exhaust. i am stuck between the Yoshimura RS-3 complete exhaust system. I like this system because of the price and the fact that it is 96dB. which is much quieter and sounds way better than my FMF mega max. the other system im looking at is the Big Gun evo-x complete exhaust. it too is between 94-96 dB. i like the looks and the price of this system as well. the third option i am looking at is the FMF power core IV with either the SS high flow header, or the fmf power bomb header. the FMF would be the more expensive way to go by about $60 anyone that has any information on which of these three exhaust systems would be best suited for trail riding please let me know what everyone thinks. Thank you

 

go with the RS-3, i personally would just buy a clamp on filter and take that air box off would go good with the cam set up if only u had a high compresion piston

 

Take a look at an HMF Sport Series .
I put on on my wife's 400EX and it made a big difference.
Comes with spark arrestor and quiet core insert.

 

if you do alot of riding in the mud i would keep your airbox on...

 

I would go with a clamp on filter but unfortunately i dont live near a dessert where its dry 99% of the time. i do ride in mud and water. i realize i would have to be cautious with the K&N lid on it. i was leaning towards the yoshi system. its the least expensive setup i can find on a good website. i have a feeling once i open up the air box lid, and put a full pipe on my ex she will wake up. i already notice a slight "hit" in the power band ever since i put the cam in it.

 

Yoshimura all the way. Great sound, fit, and build.

 

Go with the Yohsi. You will not find a better system. I really enjoy my RS3. I do mainly aggressive trail riding with a little bit of MX here and there. I had such good results on my 400 that I put a Yoshi on my 700[img]i/expressions/face-icon-small-smile.gif[/img]