| Re: MSD Ignition
Well, most modified, carbureted engines run a tad rich. An MSD will keep the plugs cleaner than a stock ignition. Other than that, not sure if one is needed on a mildly modified engine. They are used in racing to keep the plug firing under boost, with nitrous, or with high compression ratios. In those cases, you need a more powerful spark to jump the plug gap.
Supposed benefit on a stock motor is that you can run a wider plug gap, exposing more of the spark to the A/F mixture. This, and the fact that an MSD shoots out multiple sparks below 3000 RPM, decreases the likelyhood of a misfire.
One of the rags did an aftermarket ignition test within the last year or two and found minimal HP/TQ gains. However, they noted that the engines ran smoother with a high energy ignition. This is likely from reduced misfires. I have noted this on my engines as well. I have a 6AL on my 82 CFI car.
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Relatively original 1982 Z-28 with Crossfire, T-tops, and A/C delete.
Engine mods: 355 cid, Edelbrock Performer AL heads, Renegade cross-ram intake, COMP 249XE cam, 65# injectors, 2.0-inch throttle bodies, EBL Flash computer, complete MSD ignition system, K&N air filters, Hooker shorty headers and y-pipe, Edelbrock cat-back exhaust system, TCI Street Fighter TH-350, TCI 2200 RPM stall converter, 3.73 gears in stock posi rear end, SSBC two piston aluminum front calipers. | 
