Tweecer is fairly 'plug and play' once you have an EEC that supports it. Like a unichip, it fixes to the J3 service port on the bottom of the factory computer... it then interfaces with a laptop which allows you to substitute standard fuel/spark maps and scalars with your own. Remove the adapter from the J3 port and you're back to factory settings...

No support for ANY EF/EL ECU yet.

You could put the Mustang A9L ECU into your EF.. but you'd need to do some custom harness wiring, change the EF to sequential injection and use a MAF. Add in the tweecer, and set it up for 6cyl operation. I think you'd also have to ditch the DIS and go back to Dizzy. Full EL ECU loom comes to mind

For those stressing about running their Auto with this kinda setup, just retain your old Auto ECU and run it in parrallel with your AFtermarket or TwEECer compatible ECU. Let the EEC-IV/V control the Auto, and provide DOL links to your Trip Computer, Climate Control, Dash, etc.. while another ECU controls the engine. Easy!

The Unichip is spliced into the loom, not plugged into the J3.