The only problem with the solid roller camshafts and lifters on the street is the roller lifter. The roller lifters require quite a bit of
oil to lubricate the roller bearing in the lifter. When a street car idles around the lifters roller bearing does not get much
oil and has a tendency to fail after a few thousand miles. we try to use the hydraulic roller lifters and camshafts for these reasons. We have used these with great success and with the right lobes and spring pressure we have been able to get them to turn 6700 to 6800 rpm's which is more than enough with a dual plain intake. The last engine we did had a single plain intake and it made horsepower all the way to 6800rpm's with a hydraulic roller, 719 max hp and still had 710 @ 6800 rpm's.