Talk to your instructor and the folks at the field. Use whatever they are comfortable with. It will help the learning curve alot.

My tainer has a Tower .60 in it and my first kit a TF Contender has a SAITO .91. I'm trying to learn how to maintain and feed both types.

You will get a plethora of sage advice, but just do what moves ya! This is a hobby so "If it feels good, do it!"

Last but not least. 4 strokes do have a cool sound!

AL