karolh,
I have a G-26 in a CG Sukhoi ARF. I got rid of the backplate and mounted directly to the 5mm firewall, as suggested. I used 3/4" square hardwood pieces as standoffs to keep the cowl/spinner dimensions correct. I also am using a Top Flite prop instead of the APC (besides wood looks better than that awful grey color on the APC). I also got rid of my 3" plastic spinner and went to just an aluminum AMA nut (looks good because of the radial engine scale look). All in all, I saved 5- 6 ounces doing this. That is a lot of weight savings in my book. The setup weighs about 11 1/2 pounds and flies beautifully. No 3D stuff just good precision pattern. The ARF Sukhoi is the best I have owned. By the way, by mounting the rudder servo near the tail instead of a pull-pull setup, plus the weight I saved off the front, put my CG right on. I run an 18 x 6-10 prop which loads the motor down to 6100 RPM, but boy is it quiet. It just "motors" through the sky so nice. With the big prop load, I hardly have to touch the throttle through all of the pattern maneuvers (Intermediate).