http://www.rcuniverse.com/forum/forumid_92/tt.htm
This is more w8ye's territory than it is mine, but I would guess it would take at least a .50 gas engine to equal a .40 glow engine...I just finished converting a small gas 2stroke over to glow/gas mix and so far since I have no where to mount it yet, all I have gotten is a "thuka" out of it...a lot of the small gassers will also gut the muffler for power, hence the noise issue....I think the .50 gas is a neat idea and being done because it can be,,but I dont think it will go over well once tested, fuel will be less $,add ons will be more weight...just my opinion... and dont count me out, I may end up with one myself one day.....the above link is the opposite of this thread, but of conversions in general.......Rog