Mags takes more HP to run than a conventual dist. IE MSD. The reason that most sprinters run them is because they don't run batteries. I've run one in comparison to a MSD unit and saw no gain, nor did i notice any loss. The cost difference between a 6al setup and a mag is about the same if you're talking about the old style mag. i have a 6al and 7al and i don't notice any difference in them either. I don't use anything other than a 2 step and i know the 6al doesn't have all the whisles and bells that a 7al does.
JMO
Zip.