Wow, I'm surprised I didn't post the latest change in NASA's STR rules earlier; guess I've been away for a while:http://www.nasaproracing.com/rules/Super-Touring.pdf
As of 7/1/2010 (Version 4.2 of the rules) there was a change specifically aimed "Sports Racer" type cars:
For STR cars only (not ST/SU cars) the penalty for weighing under 1850 lbs (with driver at race weight) is now a factor of -2.7.
For a 1450 lb car (example from my post above) it looks my potential max RWHP would be 131 for STR2 and 185 for STR1 once factors for tires, gears, etc. are also added in. For a 1355 lb car, my actual target weight, the power levels drop to 123 whp for STR 2 and 173 whp for STR1 .. ouch, lol. That pretty much kills any chance of my "mini-LMP" type car being even remotely competitive unless I bulk it up over 1850 lbs and go for serious power.
Those looking to race a "Caterham or Lotus 7" or "Brunton Stalker" should be unaffected; They are still approved for ST competition under section 8 of the rules, ST1 & ST2 Approved Non-Production & Tube-Frame Vehicles and are still at the same +0.75 no aero / -0.75 with aero factors.
For comparison, a non-aero locost at 1355 lbs (using my same mod factors for tires, gears, etc.) would be allowed 160 whp in ST2 and 258 whp in ST1. A locost with aero mods would be allowed 136 whp in ST2 and 200 whp in ST1.
At this rate I may end up building a locost just to go racing...
I have also looking again at the SCCA rules. Unfortunately I can't see any way of getting anywhere near the minimum weight (or even regionally competitive) for an SCCA DSR build without spending cubic money on a build. Or just buying a used West or Sthor and running regionally or upgrading for national competition.