The best gas engine to replace the OS 1.60 FX at this time is the ZDZ 40. It is the smallest and lightest gas engine that will make as much or more power that a 160FX. The ZDZ's flying weight with fuel (14 oz.) is about the same weight as a Moki 2.10 with fuel(24oz.) but with lower fuel costs and the same usable power. 4.8 HP!

If you are willing to take a reduction in power with no flight weight gain (less fuel) go with the MVVS 160 gas.

There is also a chinese 29cc engine marketed by Canaday that will make the same power as the 160FX on a tuned muffler. It weighs 44oz. with ignition and stock steel muffler and stock makes about the same power as the MVVS on a pipe.