Originally Posted by nitrosportsandrunner

% of nitro is important. depending on the motor...and the tune. In other words, a 20% and a 30% will require a different tune.
to my understanding, the higher the nitro % the motor power it is possible to extract from the motor. That said, for something like a low cost redcat you don't want to tune for absolute max power...as your motor will not last as long.
20% nitro is what will likely work the best. it will have plenty of kick and speed.

Read up and watch videos about how to break in your motor. This is time consuming, but do it right and you will love that motor. Do it wrong and it will be picky, hard to tune and just a pain in the butt. Then you will curse nitro and hate redcat (cause if you take it to a hobby shop for help they will tell you that you should have bought a traxxas and that redcat is crap. this happens a lot)
Check all screws and the gear mesh before running.
Have a temp gun. It is safer to do breakin and tuning with a temp gun. It helps take the guess work out of it.

the important thing with break in the motor is to slowly raise the motor temps with each tank.

also, use a hair dryer to pre-heat the motor. They are hard to pull start before they are broken in. I had a pull cord break on me while trying to break in the motor....I did not preheat my motor. Having to wait for a new pull starter and spend $18 right away kinda sucked. Be careful of over-pulling the starter. You don't have to pull it very far.
Don't forget to do the proper after-run cleanup of your nitro. removing all fuel from the tank/carb/motor. Fuel left will attract moisture (rust) and gum up after some time.
Nitros are fun, but they take some time and work to break in, tune, and clean up.