How much power increase could one expect for the Eiger 4x4 with an FMF Powerline exhuast? What are the noise levels like compared to stock? Does it change the powerband at all?

 

I can't give exact numbers, but I can give a ride report compared to stock after it is in. I just ordered one and from what I've heard (on other boards, no one out here has one, I've posted a couple of times) there is quite a noticeable difference in the low end (same as any pipe?). As far as noise goes, all I got was it is louder than stock, but not obnoxiously loud.