I TOTALLY agree with what Milton said about the SAITO engines.
They are without a doubt the best for CL stunt*.
If you want to go big, the 72 is awesome. I consider the SAITO 30 the absolute best small 4S on the market. If you want to go a bit larger, try the SAITO 40.
HOWEVER, the ENYA engines are a very close second.
In particular, the ENYA 46 is an outstanding powerplant - I have been using the ENYA 46 and 53 for years and as far as I'm concerned, the 46 is close in performance to the Super Tiger 60.
And, of course, the OS Surpass 52 is fine and as far as I'm concerned, the best OS for stunt.
I have owned every Surpass up to and including the 70.
The Surpass 40 is the worst 4S engine I've ever used.
* - more to come!