The VEC gets spliced into the stock harness. Sean can provide the automotive grade plugs that get spliced into the harness.
There are some that feel the VEC is dated. It certainly is more labor to install than a SCT. But as of right now it still has features the SCT does not. VEC can data log. SCT does not have data logging yet, but I understand it will. VEC can control a trigger line such as water meth or N20. From what I understand the SCT only holds one tune in memory and one in the PCM. I know that with PC software more programs can be loaded. The VEC however can have as many tunes as you can get cards for. So I will have my normal 92 octane, a low octane, race gas, and a race gas with N2O. I say all that to say, I am still a fan of the VEC if you have a wide variety of tunes needed or need the trigger. However if you just want a simple tune tool, SCT gets it done.