I only put frame connectors and weld the k member in my street cars, I personally don’t believe in the core support on the A body platform (which is what I own) as the k member bolts in about 4 inches behind the rad support and that ties the front rails together.

My race cars have roll bars or full cages which stiffen the car up more than any amount of seam welding or body stiffer kit will ever accomplish...plus for the added weight I get the benefit of safety, which if you are truly going to go that fast in one of these tin cans is important to me.