We are running .550 to .600 lift at the valve on some of our 390,460 based engines. I believe the 390 that finished 3rd in the 2016 Nationals has around that much lift. With the right head work, custom ground cam and carb combo it adds a broader power band, however it is not a plug and play kind of addition. Lots of custom valve and head work is involved. Such as taking automotive titanium valves and machining them down for this application, welding up the rocker base to raise it up to accommodate the longer valves/taller lift, as well as modifying the piston to handle the valve lift.