The chassis plate 2.25mm thickness would be a nice touch as I find the stiffer you make the chassis the more consistent the performance of the car expecially on high grip (carpet).

It would be nice to have a 3mm/2mm thick carbon piece to go over all 4 screw holes for the bulkhead / posts where the top deck attaches in the front of the car.

In the front end offer a wide front hinge pin mount to change the arm sweep for more steering on asphalt.

In the front offer a wider set of hinge pin mounts front and rear to allow making it wider by 0.25-0.75mm to reduce front end response and allow for softer front end shock feel. This is different then adding 1mm shims or using the wolf axel extensions on the car.