Ignition boxes - worth it for the effieciencies

Always tell us your year and engine when asking (it matters).

I think MSD is useful more for all-out racing, i.e. strong spark at >6000 rpm. For normal driving, any of the ~1990+ HEI modules are sufficient and simpler (GM, Ignitor II, ...). The Mopar ECU is 1970's electronics and requires a ballast (less efficient). The GM 8-pin module (posts 9 & 17) is preferred because it has sealed connectors. The earlier 4-pin module (post 8 ) leaves exposed copper. The 8-pin can also be computer-controlled for spark advance.

Be expecially careful of MSD boxes on ebay. You can find posts of opened ones that have just a tiny transistor inside the mostly-empty box. The Chinese knock-offs apparently all have the same SN.