Highest flowing sbm heads?

I could be mistaken but there was a black altered at Norwalk a few years ago running this combo (P7) several years ago. My son pointed him out to me. We talked in the lanes and he told me all the stuff he made and manufactured for it. That engine lacked torque but man did it love rpm. It had a totally different sound to it from the water box out. It may have been one of the other Nascar engines as it’s been years. Probably around the time the big block Mopar TrickFlow heads came out.
There was a Duster at our local track a few years ago with a Nascar Truck engine in it. Like you said, it sounded like no other. It was tough to hook and drive because of the high rpm horsepower.