Stealth heads vs Eddy performer rpm

I'm trying to hunt down parts for my 440 build but I'm hung up on heads. I had planned on getting the stealth heads from 440 source but was told to not waste my time and go with eddy's. I don't doubt that the rpm heds are better. But they also cost almost twice as much. How much more power will I get out of the $1500 rpm heads over the $900 stealth heads?