MegaSquirt (MS3) or Holley HP EFI

DNasty777 said
I have a Terminator X and I'm starting to sour on the whole Holley ecosystem. I would definitely encourage you to really drill down on what and how you want to set up your car before coming to a final decision. If you think you are going to want to run other brand modules over CAN communication, forget about Holley altogether.

Great info. What other modules were you hoping to run?

DNasty777 said
Also Holley does not support an 8x crank trigger, so you'll need to modify the flexplate or run another trigger wheel that they support somewhere else.

Looks like the Holley dual sync distributor is another option, too.

This guy has a pretty good video on setting up a Terminator X system on a Magnum.