How much power will a stock 904 handle

Jadaharabi said

It depends on if they replaced that reverse wound spring in the clutch pack. It has a tendency to unwind and just gum up the whole works. If they replaced it I'd say you could go to 400 horsepower. If they didn't replace it I'd say you could go to 200 horsepower.
Just my humble opinion which I highly value.

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Where can this reverse wound spring be found?
I have an a500 here to build, and heavy duty parts are proving to be fewer and farther between on a 904/500 vs a 727/518.
I've never built a race car but I've seen plenty of 904s die behind stone stock 140-150ish hp engines over the years without any form of abuse...id be interested in hop up goodies and tips/ advice myself.