I changed out a k&b45 fire/turbax 1 out of my jhh mirage with a os91/dynamax, i gained 2 pounds+, but i also had to add 1 servo, 1 flight mixture, 1 fuel regulator, and hopper tank. ohh and upgraded the two 8oz main tanks to 11oz tanks.. I like the more POWER[:@]
but dont like the lump in my engine hatch cover from the size differents in engine/fan combo..

[sm=lol.gif]RaZoR