What to use for ignition high HP engine???

[markjohnson]

As stated above by PXTX, an MSD 6 Ignition is mainly for a smooth and stable idle and helps prevent plug fouling at low RPM driving.......especially from overly rich, out-of-the-box Holley's. The Mulitple Spark Discharge feature kinda goes away over 4000 RPM and there's only time for one good, solid spark. By the way, the MSD 6 box was designed in the early 70's and has some REALLY outdated electronics inside of it. The newer MSD6 Digital Box is vastly superior with modern components and is only slightly more money. It's kinda like comparing a 1970's desk-top computer to a modern, new lap-top! Anyway, I've gotta admit that I'm also a big fan of the GM Performance Parts HO HEI Distributor. It is a complete unit that comes standard with ZZ4's and 502's that has a very nice advance curve already built into it. I always keep one around and have run mid-11's while spinning it up to 6500 with great reliability.