What should I do

[Blake]

should I run boost for an autoX run or just have lots of power from the motor

[Leonard]

that depends on a myriad of factors (none of which you have detailed). Go read the stickies and then come back and try asking again when you can formulate a less general question.

[Tits McGee]

Boost is always more fun than n/a.

[Mars_302]

what kinda car to begin with? All motor is predictable. Boost can be a pain since it comes on.

[PseudoRealityX]

it doesn't matter.

[Loren]

If you have to ask, probably means you're a beginning autocrosser and Pseud is right... it won't matter. Too much power without the skill to drive it or the car setup to deal with it will get you nowhere.

Leonard's reply is correct, as well. Do a little research, even drive some autocrosses before you do any mods to your car in the name of the sport.