The chassis and roll cage design were aimed at light weight results.

To begin the rear suspension installation, the rear wheel wells and the surrounding sheetmetal was removed completely. This actually removed a lot of weight from the chassis which would be replaced by aluminum wheel tubs and panels.
Note how wide a 12-inch wide wheel looks without a tire installed!

Making aluminum rear wheel tubs

The relationship between the wheel tubs and the chassis tubing

A test assembly of interior panels

Firewall modification

Transmission tunnel and exhaust tunnel

Oil cooler mounts and anti-roll bar pivots.

The weight of the car is now under 1700 pounds. At 350 HP, which is definitely realistic, that's less than 5 pounds per HP!