Which 3S Lipo should I get??

[glassdoctor]

One suggestion if I may...

I think you should anchor the strap at the rear... drill a hole and put a screw through the chassis/strap right above the foam block. This will prevent the strap from pulling out if/when it flexes upward.

High g-force can do amazing things.... so better safe than sorry.

And add a little foam, etc under the strap and it looks good!