You should just stick with the O.S. RG untill you run the life out of it. I'd sujest the mach .26 (if you can run .26 engines) or the sportwerks .21 (but you might need to get a starter box for it... the SW .26 pull start might work).

I raced through 4 mach .26 engines and have won quite a few races with them. Very easy to tune and they hold it well and all of them lasted between 5-7 gallons running a little lean. Very linear power so you get good bottom end power for those tight corners and pleanty of rpms for a short 100 ft straight away (but what nitro engine wouldn't [sm=tongue.gif]). For only $140 its a great buy and I loved mine.

Right now I'm racing the Sportwerks .21 for $180. TONS of bottom end power so you will need some good throttle control and raise your gearing a little. The RPMs tack up very fast and it has a fairly high max RPM so you get more MPH. Running a 14t clutch bell gear on my MP777 with this engine it still has more RPMs left in it at the top of our 135ft back straight away. This engine is perfect for tight tracks and I can promise you it will keep up with or beat any engine on your track because those high dollar engines just don't have the room the stretch their legs. Its very easy to tune and holds a tune better then any engine I've ran. I ran it in 40 degree weather and in 65 degree weather... only needed to richen it up 1/16 of a turn in the 40 degree weather and it ran just like it did when it was 65 out.