Dave,

I have an Extra 300s with a saito 100!! WOW!! unlimited vertical at 3/4 throttle.
No mods during the ARF buildup, just built it like the manual sais.

This airplane like to fly fast, it gets mushy when airspeed is too low. I have an older extra with an OS 91 four-stroke but does not have the performance of the extra with the Saito 100 ( I call it 'Extra Strong' ).

I have been flying extra strong for about a year now and it is my favorite plane. I am running 15% nitro and an APC 14X6 prop. It is plenty strong and I always run it rich (@10200), I have no need to peak out the engine because it is so powerful that even running rich I have great performance. It does require a good chunk of rudder during take-off to keep it straight on the runway. And landing...well just keep a little speed and don't slow it down too much.

When I first put the Saito 100 in the airplane, I was doing it as an experiment in power, but I am glad I did, The Saito 100 weighs less than the OS 91 and far outperforms it. I would recommend this engine for this airplane, It may seem like too much but it really is a great combination.

Good luck with your extra, I'm sure you will have a blast with it.

MR G