What will an MSD actually do for my car?

What are they made for?

 

It is like a stereo amp for your spark plugs. It is going to give you a much more powerful spark, which will be important if you start doing other mods to the car, such as forced induction or NOS. Another benifit of the 6al, it has an adjustable rev limiter, and you can piggyback other ignition controls, such as timing retards onto it.

Personaly, I would go with the Digital 6 over the 6al, cost more, but is a better system, and has a lot of the 'add-on's' already in it.