Yeah, I can understand why some would not give out certain details. But, especially for some of the GT classes, there are mild combos that will run just under the index. That's quick enuff to win any race, unless you have a same class heads-up run.
I've noticed that Lindy Lindholm has started running his 2nd gen Stocker in GT Super Stock. It runs barely under the index. Would be interesting to know what engine changes he made, if any. Although some porting, roller cams, alum intakes, and wide tires are legal, don't know what changes he made.
At the recent Vegas race, he only ran an 11.28. But that was good enuff, for non heads-up runs. Larry Maxwell also ran an 11.28, with his 350 powered '68 Bird.
https://www.dragracecentral.com/DRCS...r2018#indextop
Hey, there are a LOT of street cars here, running quicker than those guys. So, you wouldn't have to know any real deep SS secrets to build a GT Super Stock car that will runs it's index. And, if you don't have a lot of exotic parts in your engine, you can run some of the big bucks bracket races with the same car. There are quite a few Stock racers who run both, with the same car.