I have a 98 Heat and just added a GT 509 (540 hp) in it. Will i benefit adding a shorty to it, and if so what prop would you suggest.

As a side note I am looking to add a whipple in the future?

Thanks

Take a look at "28 Heat prop issues" that I brought up to the top for you for an extensive discussion on this subject. It looks like several guys are doing similar mods. I hope this helps.
Regards,
Steve