Originally Posted by 356-930 (Post 4916917)

There are three different MSD “systems” that can be employed to improve the 930 engine’s performance:

a. P/N 6462, aka MSD-6BTM, has an integral boost retard controller, providing for a boost controlled retard rate from 1 to 3 deg/psi, maximum 15 deg. Retard onset pressure is fixed (starting at 0 to 1-PSI?).

b. P/N 6460 with P/N 9762, aka MSD 6AL with Boost Control Module. Improves on a. by giving control of boost retard onset pressure from 0 to 5psi.

c. P/N 6460 with P/N 8977, aka MSD 6AL with Multi Function Ignition Controller with Boost Control. Improves on a. and b. by providing control of ignition timing by rpm and boost retard onset and rate (up to 25 degrees retard). Boost retard is "additive" to any timing map. In other words, lets one build a detail/custom timing map.
This digitally controllable system can be used to eliminate the distributor’s vacuum/boost advance/retard and mechanical advance.
Not an engine management system (EMS) but rather a total ignition timing management system (TITMS).
The system uses PC based Pro-Data+ software (free) or for the non-computer racers, there is a hand-held Programmer Monitor ($229).

Factory costs:
a. $415
b. $513
c. $729

Re Rotor - These systems generate/put out a major amount of energy. If the stock ignition rotor has a resistor (buried in the black epoxy bed, center top of rotor), it should be dug out, a 12AWG solid copper wire soldered in its place and re-epoxied. (There are those who have never eliminated the resistor and had no problem and there are those whose ignition failed on the road, on the track when the resistor became toast. Resistor roulette doesn’t seem a smart game to play.)

Re Tach Drive: MSD has a 12 volt square wave signal with a 20% duty cycle. If the stock 930 tachometer cannot accept this signal, add/use MSD P/N tach adaptor ($65).

Re Rev Limiter: MSD-6AL series uses a rev limiter "module," a small 2-pin device that plugs into the bottom of the ignition, set for a specific RPM. Available in 100-rpm increments i.e. 6500, 6700, 6800 etc. NOTE: If the module is removed, falls out, No rev limit. Mounting the MSD-6AL upside down makes sense.
Unknown how Multi Function Controller (P/N 8799) handles rev limit, most probably via software.

Of the three systems, I vote "c." for a CIS-930.