i have a 1998 bravo 1 on my 26 sonic with 502 efi that i'm thinking about super charging with vortec charger which will produce about 575 hp . i'm going to run 4-5 lbs of boost because of only able to get 89 octane fuel. what if any upgrades are needed to keep the drive from breaking ? where do i get the upgraded parts and cost ?

I'm running a stock Bravo 1 on my 24' pantera with 650HP. So far so good. Just ease it out of the hole and you should be fine.

I'm building a back up just in case. The newer gear sets are more durable than what you're running now, thats a good place to start. Or step up to a ZX or XR

No upgrades are needed. Just be easy with the throttle, especially when planing, and you'll be fine.