Torqstorm.. let's see how it does

Super charger/Turbo = 6 or one half dozen
The engine is seeing pressure and exhaust it. Perhaps the amount of pressure an engine see’s could vary that exhaust a bit? IDK myself.

At the described HP level, I don’t think a 3-1/2 exhaust pipe would hurt. But…….. I’d dyno it and find out how much tube added on to the collector would be the best benefit. At that point, add a pressure termination box and have it exit with the same size pipe into a likewise diameter muffler