I just got my BMI setup and ran it for the first time last night. I was running with the fastest guys at our club when I didn't screw up. Overall I qualified about 1 lap down from them and I used to be 2 laps, or more, down with my stock chassis. I was very impressed. Still need to get my ride hight correct. I was picking up traction compound on the bottom of the chassis.....too low.
As for the battery strap. I had my battery slip a few times in my first practice runs last night when I hit the boards. I took the body clips off and put a washer under the screw and just tightened the strap all the way down to the posts. That seems to snug the batteries up a bit and I didn't have any more battery movement all night... and it's still easy to take batteries out by just loosening the screws and slipping the batter out from under the strap.