I am thinking about buying the FMF pipe. How much power did it add? Thanks Guys.

 

I do not have a Powercore IV-2 on my 400ex, however I do have the Powercore IV. I am really pleased with the increase both in Torque and HP. I don't know what the exact increase in power was, but it was tremendously noticable. I don't really know what all the differences are between the Powercore IV and the Powercore IV-2, but I heard that the Powercore IV-2 is a little bit quiter then that Powercore IV.

If you plan on getting a new FMF pipe for your quad, I would also suggest getting the K and N Powerkit as well. When I first got my pipe I did not have to re-jet my 400ex. It ran fine without having to re-jet it. But when I bought my K and N kit I had to re-jet it due to the new air filter.

Fourtracker14

 

White brother's all the way!!! I think it way better than any fmf out.

 

I have the IV-2 and powerbomb header, plus a K&N. I gained considerable mid and top end, but the increase on the bottom was less dramatic.

 

In the pipe shootout which they used a 400ex in dirt wheels the e-series slip on one. I have it on my 400 it is great it is also like 5 decibels quiter which is good now a days. Here is the cheapest place for this www.gopartsdirect.com $215.00 plus free shipping I have ordered alot from this place they are great. The nice part about the e-series you don't have to re-jet right away you can slip it on and go.
2002 400ex
ac nerfs ( these look great on this quad)
ac bumper
K&N power kit and filter
w/b e-series slip on

 

I`m going to get the TC Racing exhaust.