cheapest way to get hemi 3g going?

In order to get Megasquirt to work with a 2003-2008 5.7L Hemi you need to do a couple of things:

1. Convert the drive by wire throttle body to a cable operated throttle body. FAST sells an adapter for $68.00 that will allow you to bolt on one of their 92mm throttle bodies. I made my own adapter, all you really need is a drill press.

2. You need use a GM style throttle position switch and a GM style Idle Air Control valve, with the FAST throttle body as it is an LS style throttle body.

3. At a minimum you'll need to use the following stock sensors:
Intake air temperature sensor.
Coolant temperature sensor
Camshaft position sensor
Crankshaft position sensor
You can use the stock wiring harness to connect to a pigtail you buy from DIYAutotune.

4. The MS3 and MS3X do not put out enough juice to fire the factory coils, unlike the Chevrolet Coils which have built in ignitors, the Hemi Coils need an external ignitor, so you will need two of these:

http://www.diyautotune.com/catalog/quadspark-four-channel-ignition-module-p-481.html

This should get you thinking.

Regards,

Joe Dokes