The 20cc gassers are about equivelent toa 1.20 FS but a .60 2 stroke is just under 10cc. There are some 15cc gassers out there but the 20 seems to make the most sense all around for planes in the 10-15 lb range for scale flying. I have the DLE 20 in my 11 lb TF P-40and it flys great at a little less than 3/4 throttle but put the petal to the metal and you have war power babyThem zeros don't what hit them. The weight of my DLEis 30 oz with muffler and ign. I actually had to mount my radio battery at the trailing edge area of the wing to get balance on my ryan, I hung it under the wing bolt plate.