Great point Carter,
As one of the "veteran" Spec E30 racers, let me offer these thoughts:
I agree that having the newer style bumpers offers a slight performance advantage. That’s some 30-40 pounds located at the extremities of the car that could be more efficiently placed closer to your CG. I’d agree that this is a fair amount when messing with weight distribution/balance.
Now, does it really make a difference in Spec E30 racing? No.
If I were building the ultimate time trial car, and wanted that one perfect lap, then I’d go for the newer bumpers. But a newer style bumper isn’t going to do squat for you when Chris Cobetto is 2 inches from your fender in the middle of the turn, making you as un-comfortable as heck. Getting wheel to wheel is the great equalizer here - and the measuring of thousandths gets zeroed out.
If anything, Carter’s stonewall stance on bumpers is going to save you a few bucks, and the headache of swapping over the bumper.
Get the car built per the rules as they stand, and come out racing. I promise that you’ll never look back!
-Vic
SO #325, and "veteran" Spec E30’er