Have a Sig Mahem w/ 1.20 2 stroker. Very nose heavy. Plane in at about 7.5 lb.
Would it be worthwhile to use a 7-8 oz battery in the tail to offset the heavy motor? aka 5cell 2700mah*
Would this create a "moment arm" that may affect the 3d performance? No other options other than relocating the servos that I see at this point and I don't really want to do that.

Any suggestions?

I do not know if you have the funds, but why not try the
new OS 120AX at 21 oz with out the muffler and the size of
the 91FX ?

...Sounds like the easest fix...[8D]

yeah if the weight problem is that serious, sell the engine and go with something else... still easier than relocating servos i think