It's not hard to get power out of a Y. It's just more expensive due to the relative lack of aftermarket parts.
I think, on the street, most are under 300hp. 300 - 400hp is not uncommon. At the Y-block nationals there are race cars which are probably in the 500+ area. The most powerful is probably Randy's railer which dyno'd at 750+ if I'm remembering right. But they had to stop the dyno pull at some RPM for some reason - and the power was still climbing.
When you consider that we have little to work with, particularly in the head department, as compared to other motors, these power numbers are extremely respectable. Can't wait to see what happens with the new heads.
What's most important for the street is torque. And the Y does not have a problem producing torque.
Lawrenceville, GA