Free speed mods

This is my first post, and I've been lookin around this forum for about 20 minutes, so if I ask anything thats somewhere in the annals of this board, forgive me. Anyway, I want to make my Microsizer as fast as humanly possible. I've got gears and a 3.8 on the way to me at college right now, and I've got full access to basically anything I need electronically or mechanically that I would need to make modifications. I'm just fishing for any more ideas from you people.

I was considering dual motors, but would that really be worth my time?

Does anyone know which resistors I have to swap out on a Microsizer, I only found the post about the ZipZaps resistors.

And has anybody overdone it and fried their circuit or their motor, anything like that. I need as much user feedback here as possible, cuz I just LOVE tinkering with stuff, but I don't wanna have my car explode mid-race.

Thanks in advance for your help guys, its much appreciated.