340 HP's vs headers

To kill a 150 hp on a 450 hp engine would back to stock 340 hp numbers. Air compresses my cousin's stock car engine pulls to 7000 rpm with a 2 bbl making well over 400 hp. Nascar makes 800 hp with restrictor plates with dime size holes.

Obviously manifolds aren't the best idea for performance. But with a little planning can't see why you can hit your goal of 400+ hp.