Well, I pulled my exhaust to weigh and measure it for an Ebay dispute I'm going through, and found out something interesting... there was a MASSIVE weld bead right inside the exhaust port side of the exhaust header. I mean, this thing must have been 1/8" tall and circled all the way around the inside of the joint between the pipe and the ring that's welded on to mate with the gasket at the head. Anyway, since it's so easy to pull your exhaust, I recommend checking this out on yours. I used a half-round file to knock the ridge down to almost flat. ALMOST flat because I didn't want to go too far and weaken the actual weld.
I think this will make a difference, as the weld bead is so tall that it actually significantly reduces the inner diameter of the pipe right at the exhaust port. Such a tall and almost square bead will cause turbulence, as well, which will act as a 'virtual' restriction. Turbulence is bad, laminar flow is good. Not thinking I'm getting anything like laminar flow, but DAMN you should see that weld!!
Also, pull out your spark arrester and check it out. I never realized how much of a restriction it is. When I run it without the arrester, it really feels like it accellerates better. Sounds cool, too. Has a throatier sound, and a more muscular tone, rather than a put-put kind of noise.
I'm gonna try and build my own spark arrester that's not such a restriction. Should be do-able. BTW, mine didn't have any carbon build up or anything like that clogging the screen like some people have noted. I have about 240 miles on it since new.
I ran it without the muffler for a minute or so, just the pipe, and WHOA it sounds like a freaking race bike. Put in some ear plugs! Too bad FMF is so damn slow with the Eiger stuff.
Just some more info for the Eiger guys...

 

Sounds like you have everything off that beast at one point and time. I heard rumors about Big Gun coming out with a new exhaust for the Eiger, haven't seen it yet though. Keep us posted on you spart arrester.

 

Thanks for the heads up on the exhaust port. I'll check it out as soon as I get past a problem I've encountered trying to get to my main jet. I can not remove the screw that holds the plastic cover where the thottle cable attaches to the carb. I used a new screw driver but no luck. Any suggestions?

 

Before the screw gets too crazy bunged up, I'd go buy one of those #2 phillips screw driver bits from the hardware store that's for installing deck screws. Seems like they have really sharp edges that bite good.