You will want to have MS run your injectors. Tune your fuel, then once you get the hang of it, have it run your injectors and coil pack.
Setup:
MS Hardware: MegaSquirt Version 3 PCB Neon/420a Input and Output mods done to the MS board Run the Mitsu Power Transistor (from junk yard) to fire coil packs from MegaSquirt spark outputs.
You can use your stock temp sensors, but calibrate MS using EasyTherm (search msefi.com). Or if you want you ECU to use the stock sensors (for better idle), just put extra GM temp sensors into the intake and coolant track.
If you want 300whp, the Mitsu power transformer may not work right. Upgrade to either a crane ignition amp or: check out the Tach spikes posts in this forum and see how to mod the crank sensor input of the MS to a VR setup. Then, use the VB921 coil drivers inside the MS instead of the Mitsu Power Transformer.
Software Setup: MS1-Extra (MSnS-extra) version 029t
That should get you started. But learn how to tune your car. You will learn much more about engines, and you should know how to tune your car regulaly. What happens when you change some intake pipes, intercooler, put on a bigger exhaust? You going to keep going to the dyno? Nah. Its more fun to know what your doing and just take 10 min. and retune.
