It doesn't seem like you need any more traction for what you're doing, so I'm thinking you might actually want some hard[er] rubber tires, maybe like 30 or 40 degree compounds, so you can kick the rear end out a little bit and turn tighter. Less rolling resistance also isn't a bad thing with your lack of power.
A very nice chassis overall, I'd personally use some thicker material to improve chassis stiffness a bit. That, or use liberal amounts of glue attaching the battery holders (did you already do that?) to make the battery holders contribute to chassis stiffness.
It should also look a little lower once you get that Evo board in. Good job!
