My RST made 270bhp on standard rods/pistons and about 28psi of boost. I have run as far as 30psi, but my engine was very low comp.

I now run around 25psi with my steel rods, not sure how much power yet, but I would think around 300bhp.

As for breaking point of Steel Rods, I would say that you are more likely to have an engine failure due to a poor machining tolerance or a badly assembled engine LONG LONG LONG before you break a Steel Rod. IMO the Pistons will always be a weak point, whatever they are. Even if they are fancy forged jobbies, doesn't mean that our good friend 'Uncle Det' wont blow a big hole in them if he decides to pop his head up. The crank will also become a weakness, but only if you plan to run silly revs (8k plus?)