Joe, thanks for the info. I had a big response typed up and the computer froze.

That 1.40rx is definitely a great engine. I love the performance of the big OS 2-strokes on 5% - 15%. I had a 1.60 with mixed results due to the Pitts muffler (deadsticks), but it handled very well. I especially loved the 12+ minute flights on 14 oz of fuel. I could probably get a NIB 1.60fx, bearing, pump, pipe, header for about $500 or so.

The 1.40RX is an excellent option too. It has two problems though. It requires that I purchase a full-length pipe ($160 - $275) and it requires that I install said pipe (long pipe tunnel). I see the engines for sale from time to time used, but buying new will cost as much as a 1.70DZ.

On a side note, I am interested to see if OS follows suit and releases a big AX series engine (1.80AX? 200AX?)

My plane has a short pipe tunnel for the short 4-stroke pipe. I want a relatively plug-and-play option. I know the 2-strokes will blow it away on power, but power is adequate and it is easy to live with and costs $399.