Hydraulic rollers in production engines like the LS7 7.0L that turn 7,000 rpm with a 100k warranty wasn't in anybodies wildest dreams back in the '60s/70s/80/90s. Heck, 10 years ago we would have all thought that this kind of performance was impossible. These are street grinds with over 0.600-inch valve lift too. Sure, solid flat tappet cams can make more peak horsepower at the strip, but it can't touch rollers for the area under the curve and all round street performance. PLUS you can reuse roller lifters as often as you want.