Dealing with drag radial cars on nearly a daily basis I definitely know what is required to go that fast. Dipping into the 4s every now and then is one thing......to consistently run mid 4s is an entirely different matter. It takes a REALLY stiff car to do this. Cars that run mid to low 4s are built like Pro-Mods on small tires for a reason. Your changes will definitely help, I was only pointing out a few things I thought would make it better.