I have a OS50 and it makes it ROCK!

Have a Madness with the YS45 and the 50 has substantially more power. The YS would allow for mounting the tank way back in the fuse. The 50's power more than makes up for it.

I have a 61 FSR, and it weighs allot more than the 50. CPLR flys his with a OS46, and that is the motor it was designed around, so the 50 gives it the extra boost.