Obviously, I had some learning curve climbing completed after running an MS1 setup on my car for years, but the second setup I did with it was just dead simple. I got an MS3X box with the two pigtails. It just had all the available functions already hooked up internally, and the pigtail was labeled on each individual wire. I never had to crack the case open (other than out of curiosity, when I got it).
The MS1 was a plug-n-play - it mostly interfaced with the engine through the stock engine harness, with an adapter harness made from ECU plus that plugged directly into the harness. Over time I added more functions and added wires.
For the MS3X I just redid the whole engine harness from scratch. Un loomed it, took out all the unused junk, added a bunch of new wires (DSM CAS, sequential wiring for the injectors, COP wiring). This was pretty simple to hook up to the MS3X pigtail, though.
The MS1 was a plug-n-play - it mostly interfaced with the engine through the stock engine harness, with an adapter harness made from ECU plus that plugged directly into the harness. Over time I added more functions and added wires.
For the MS3X I just redid the whole engine harness from scratch. Un loomed it, took out all the unused junk, added a bunch of new wires (DSM CAS, sequential wiring for the injectors, COP wiring). This was pretty simple to hook up to the MS3X pigtail, though.