increase HP on a 273

Mike...I hear lots people recommending the E-4 cam. Can you tell us how it "feels" (drives) compared to, say, a stock Commando setup? Whats the idle quality like? Low end torque? I'm getting a pair of "302" heads done as we speak for my '67 Dart 'vert, and was considering a cam change at the same time. Is the E-4 a hydraulic or solid cam?

Thanks for the input.