I ran in STH for an entire season on stock springs and shocks, but with the largest FSB I could find (Hochkis) and the 034 rear bar on full stiff. I ran solo nationals like this and placed mid-pack, but beat my local competition.
I had great grip, but, the rear was very planted, so an overall understeer at the limit car.
When I added 400 lb springs front and rear with the Ohlins the next year, I had all sorts of issues with massive understeer. It took me an entire season of shock setting, different springs, different swaybars and progressively less rear toe in, to get to a place where the car started to rotate. And then my RE71r's were heat cycled out. I also had a hard time beating the local competition.
If I'd went stock shocks and springs route again, I would immediately add 1/8 inch total rear toe out, with all bars on stiff, with as much front camber as you could get.