what is the best exaust for the cheapest price i can buy for my 400ex?

 

white bros E series

 

check rocky mountain.

 

I personally think the WhiteBrothers R4 is the best bang for your buck that is what I'am running on my 03 400ex and it is great with the E series you have to mess with disks and what not the R4 has better performance gains and I belive it is cheaper. Plus that is what WhiteBrothers runs on there Championship winning 4strokes.

 

I had a WB R4 on mine and I loved it.

 

if i intalled a 440 big bore kit on my 400 would i need to get a bigger gas tank or will my fuel economy still be ok?

 

i would still go with the e series, it adds the most hp for a 400 ex

 

with the e series do u need to jet?

 

You should re-jet with any pipe. The E-series pipe has agood power curve but the quality is awful. There is 2 in my garage and they have both broken in one way or another. I wouldn't sell mine to someone I had to talk to or look at, that is how bad they are built.

 

we have fmf and it broke also.