Unless your ignition system is really down and out you won't see a noticeable increase in power or efficiency by going to a more capable system. I know that and I do it anyway. But take a good conventional system and install a high $$$ CDI and there will be only a slight improvement, if any. The "placebo effect" assures that you will probably notice an improvement, but this is because you expect it to happen, even if it does not.
R.
^^^This.
On my drag car, I ran a stock chrome box set up, stock distributor with Jacobs coil, complete Crane system, A complete Mallory system, and a complete MSD system. All of them ran the same e.t. and m.p.h. none really outperformed the other. Each offered a change up in features that were nice to have, but didn't make things run any better.
I'd say the coil on plug set up is the next best evolution.
