Originally posted by InitialD
Get the Dragon. It is the later version. For the price and performance, it's quite worth it. In fact, the STS engines when tuned correctly can rival the better Italian engines.
I'm still running the RS3 version. Look at this thread discussion here. The STS RS3 is supposedly a hand modded engine but with normal glow plug. I changed the carb to a bored out Nova one (6.3 mm) and it flies. 
The only problem I had with the engine is the piston and conrod bushing wore out pretty fast. At least this is what I experienced. Changed it to a 2nd hand Nova piston and conrod. Used back the same sleeve and everything works perfectly. Maybe the newer Dragon has better materials.
STS price is quite reasonable but does it easy to get parts for engine..lets say the Nova piston and conrod and sleeve? how much would it cost for nova sleeve and piston??
