The original blowers they came with , the 420 B&M, will support around 1000HP, with the right combo underneath them, and a chiller. Stock pulley ratio on them was 7% underdriven, and made 5-6lbs of boost. Blowers are fully anodized inside and out, including the rotors. Stock carbs were twin 700 CFM holleys.

Simple mod for more power, would be an intercooler, and more boost, taking them to the 700HP level. More involved mods, would be better heads, bumping the compression a bit, better cam, larger carbs, taking them to the 800+hp level.

In stock form, they were very reliable. Very similar to the 575sci, with basically a larger supercharger, and carbs instead of EFI.