Great thread, I like your work on the car and results obtained
I have modded cars for decades and have one of the most modded ST's there is but do not have any chassis braces except a two point up front as did not see a benefit to them due to how the car is designed. My car was on a lift at a major race shop and the manager took a good look at all my mods, after he had driven the car, loved the car, the mods, etc and we talked specifically about braces and he agreed with my opinion and execution.
My 2 cents on chassis bracing on this car, I could be wrong and it now seems I will be keeping the car so will explore this a bit more but likely stay with what I have done.
My two point is a 1" sq fairly thin wall steel tube cut at 45 degrees on the ends to allow bolting through it to the subframe.
Subframe was drilled and nutzerts installed to bolt it to.
Cost, scrape metal and parts on hand, barely any.
Time to build, less than 30 minutes.
Time and cost to replace if bent, I was on the road so had to buy the metal, scrap yard, new material, $2.
Damage to chassis from hitting the brace on something on the road, barely bent mounting points.
I am a staunch believer in removing every bit of weight I can reasonably do and only adding weight where I am positive it will be a benefit to overall performance of the car.
Since I do not autocross much any longer there may be some things that work for that use I would not need for mine, built for HPDE and TT events.
I have used plenty of braces and built caged cars up to one with a huge number of tubes, all I needed were new bottom tubes and could not even have a body.
My personal opinion is many parts are sold for this car that make money for the manf but not really needed and those parts make the car slower, the money could be more wisely spent to make it faster instead or get more seat time which we all need
Most sincerely,
Rick