Thanks for the info David. I had the GG15 on order for a month and a half and it just wasn't happening. So I opted for the GT15 and got it promptly so here I am. There is a 4 ounce penalty for the IBEC/CDI modules but no extra ignition battery required. It should make a very nice power plant for Escapes, UFO's or slightly enlarged Kaos.
I take it the GGT is quite popular then. If you get any feedback on them from users including pipe response and performance, please drop me a line. I'm thinking of inverted later classic applications more so than the early ballistic designs as inverted gas and 4-stroke seems to generally work better than inverted un-pumped 2-strokes (i.e., factory YS/OS engines). I'm actually putting the fine touches on an "aerobatic" P-51D I designed intended for 1400W of power. All power plants are doable but IC's have to work well inverted. Being a Mustang, 4-stroke 90 power struck me as the most logical although electric is also possible. I really didn't want to run an inverted 60 with SE on it as it is cumbersome and it wouldn't sound right to me. I'd rather do electric than that. But... a sensible gas 15 would certainly be a good option to a 4-stroke 90. Correct me if I'm wrong but I believe the gas 15's have the same mounting pattern (dimensions) as OS 60 size engines (FSR, SF, FX, AX), yes?
BTW, why is there no need for an ignition battery on the ignition GT? Are you using the same battery used for the radio?
About 25 years ago we ran stretched pipe 60's (Rossi's and YS's) turning 12x12, 13x10 props at around 9500 give or take on the 70-74" spanned models of the day. The GT15 is putting similar output to those set-ups on its muffler but is quieter because of the soft iso mount.
Sounds good. Let me know what you find on it once piped.
Thanks, David