The reason for using a rev kit is to prolong the life of your valve train. Some engine builders have found out higher spring pressure makes more HP and higher revs. The downside is that when you run over 300lb of spring pressure your valve train doesn't last as long. The bad thing is most engine builders want every single HP to look better to the competiton. If you run a rev kit you can run around 200 to 220lb of spring pressure. The rev kit will be good for around 40 to 50lb of extra spring pressure. As you can see your valve train will last alot longer with 220lb of spring pressure compared to 300lb and up. The downside is you have to run horizontal roller lifters and you have something else to go wrong. I have gotten away on my last 2 engines, mainly because many of the other parts I'm replacing sooner, but when I did run one, my valve springs and valve train lasted twice as long. For a budjet race engine I'd say yes, and for a high dollar race engine no. JMO