I mentioned in a simular post, that the 284/484, and 292/509 purple shaft cams were designed for beacket racing. These were the cams of choice in the Mopar Performance catalogs if you were building a bracket race car (hi-stall converter, open headers, and 4.10+ gears.) The 108 lobe seperation angle tends to create a strong, but narrow torque curve in the mid to upper RPM range.
Because of the increased overlap, the idle is choppy, vacuum is low, and low end torque is fairly weak below 2,500 RPM.

The newer "street performance" cams use a slightly wider lobe seperation angle and split intake/exhaust duration to provide a wider torque curve that will still perform good in the upper RPM range, but they may not have as much "peak" torque as the Mopar purple shaft cam.