I recently was given a FMF Powercore IV exhaust from a friend who bought a new exhaust for his 400 EX. It looks like it is pretty easy fab to make it fit. I have got a new main jet (130 stock to a 140), but have yet to install it until I check the plug after a few test rides. My question is should I expect loss of torque or power from this exhaust? I know it is a sport exhaust, but wasn't sure what to expect. I am sure that there are some design differences for each type of riding (racing vs. trailriding). Has anyone done this, and what was the effect? I look forward to hearing the old Kodiak with this new pipe.Thanks for your help.

 

How did it work for you?

 

Well I am very pleased with the new exhaust. I cut the old pipe just behind were the slip joint is, about 12 or 14 inches back from the joint. My friend Tig welded a piece of chrome moly tubing on the original pipe that went perfectly into the new pipe coming from the Powercore silencer, with no clamp there is no exhaust leak. It was a complete system that was on the 400ex. The sound is awesome, it is some louder, but not annoying. The sound of the Kodiak going thru the woods is awesome. I have noticied an increase in power thru the powerband, it pulls off the line like a bear, and I didn't lose any topend, still about 55 mph. Went riding with some friends 2 weeks ago some fellow FF's who have stock exhaust, after a day of them riding behind me they are ready to find an aftermarket pipe for their atv's, they really liked the sound. I have to say it was well worth what I have in it, FREEE!!!!! BTW I have not rejeted yet, with a Twin Air filter, the plug looks fine. I even had my neighbor check it, he builds sprint car engines for a living, and he said the plug looked great. I thought it always ran rich.