Looking back through the special editions of Autocar & EVO magazine on the Maca F1, apparently there are only three things GM would change...
1. Brakes, they apparently tried ceramic, but couldn't get them to work for general road use, so ended up using steel with hard pads..leading to high pedal pressures & squeal when cold which wasn't ideal apparently!
2. Lights, although good for the time, they later offer a Xenon upgrade, oblong shape for one with a projector Xenon which looks different to the two round factory headlights, & easy to tell those cars with the later upgrade.
3. The bracket for the engine bay light switch. This was changed from the original design after the sign off by GM, so he knew nothing about it! Apparently the engineers found that the engine cover would move (very slightly) at very high speed potentially causing the engine bay light to come on, so they moved the position of the toggle microswitch, adding a new bracket to support it & didn't tell GM!!...