I should add that my Dad's 500 has the same engine set up as mine but is running a Q V1 pipe. I does have a lack of bottom end. I would not recommend it for trail riding.

yea the Qv1 comes on much later than the others, like 5300 RPMs if i remember right. 

I ran a AAEN pipe on my stock cyl 87, it didn't have the low end of the previous fmf that was on it, but was much better mid and wayyy more top

I seriously doubt that you'll feel much of a difference between the others and a FMF.  It's less than 1k RPM.  Could of been a jetting issue.