Actually, the solid roller doesn't really have much more peak rate then a flat tappet. It just holds the rate much longer. There is a gain to be had here if the roller has the lift, but the best bang for the buck is the solid flat tappet up grade from the Hyd. The gain is the biggest when switching from a hyd to a clearance ramp cam. The roller won't change the manners of the motor like response and power bands much over the solid, but the solid will drasticly change them as well as the motors acceleration rate as compared to the Hyd. Think about it: if a guy has an adjustable valve train, the solid cam and lifters are very close to the same cost as the Hyd cam and lifters, but to spring for the roller conversion, he is going to spend another grand by the time he buys lifters, an extra $100 or so for the cam, big Springs/Ret/Locks, etc. I consistently see small & big block chevy's and 5.0 Ford's with perf. hyd cams in street attire shave well over a full second off their 1/4 mile times at the strip by switching to a solid lifter cam and with no other changes to the car or motor whatsoever.
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