Stock my car was 430/420 at the wheels. I got the evolution stage 2 ( jlt intake, tune, 2.6 pulley, plugs ) 521/519 at the wheels now. I also have Bassani race mufflers but there is no gain with axlebacks really.
If you want stupid power get a whipple 3.4 or kenne bell. The ford racing tvs blower has a lot of potential as well.