I think it's an awesome class as far as rules go, as-is. I raced my almost bone stock GN at Reynolds years ago when my T was getting a rebuild, even though I only ran low 13's. Anyone that hasn't raced heads up should try it, no matter what time their car runs. It's fun.
The spirit of the TSA rules has heavily influenced my car for sure though, even if I can't race in the class. I'd love to make my car TSA legal, but it's too far from stock to go back at the moment. I don't even have side view mirrors. Lately I've been moving more towards making the mods stock appearing, case in point, I removed my A pillar triple gauge pod and I run most of my stock turbo shield instead of no shield like most do to save weight, and a stock reproduction AirResearch tag on my V4. I even drive around with a complete stock airbox from time to time, 11.2 at only 15-16#'s boost with it, though I've gone 130.8 mph in the 1/4 on the stock 2 screen maf and hose....
Maybe one day there will be a class between THS and TSA with minimal rules, have to run the stock airbox, 3bolt TA turbo, SLIC, most of a stock turbo shield, working A/C, 8.5, 200, no trans brake, 3500#?