Search around and I think you'll find a lot of stuff on this. I think the '88 2.5 TBI cam had the most duration of the rollers. I put one in my '85 T1 and it's quieter than the slider and seems to be a little stronger in the mid and upper rpm range. That's going by seat of the pants, though. Also, if you have a slider, the roller gives you a bit more power just due to less friction.