[blykins]

Ernie, I usually aim for around 5500 with a hydraulic roller. Considering if you're running through the gears, you usually shift about 500-600 rpm higher than peak hp rpm. I feel that's pretty safe for a hydraulic roller cam and if more hp/rpm is needed, then I go with a solid roller.

You can go higher of course, but you have to start looking at higher pressure dual springs (or beehives), lightened lifters, titanium retainers, etc.