the highest octane i can get is 93. would it be worth it to get a 13 or 12 piston from a 10:1 for a 450r?

 

You "might" get away with a 12 to 1 but it's going to be close. You might run it for years and never have a problem but then again on a hot day at sea level you may burn it up. If you do put a 12 to 1 in it and run 93 you better know how to read plugs or learn real quick.
With a 13 to 1 on 93 your going to be picking aluminum out of your pipe.
But then again, detonation is determined by a lot more than static compression.

 

Yeah, 12:1 SHOULD be OK, but definately not 13:1 (or anything higher than 12:1)