I think 550whp is like the minimum most supercharged cars put out. Theres N/A cam cars out there that are over 500whp. Not sure where you have seen 450whp supercharged cars, unless they're pushing 5psi or something. 600whp is easily obtainable on a stock engine with S/C.
2010 Camaro SS LS3 - Torn down after cam/oil pump failure. Rebuild in process!