I like stock rockers because of their simplicity, cost, and that they are part of a total engineered package. The only drawback is that the ratio is all over the map. What I did years ago was get a bunch of rockers and check the lift on each one. Then I split them into intake and exhaust sets that had approximately the same ratio. Worked well so far. As to the technique, it isn't mine, Racer Brown was promoting this 35 years ago.