I bought an SCT for mine. I picked it up very cheap, people are practically giving them away. A mini maxx would have been nicer to have, but I couldn't justify the money for one. You will have to get custom tunes like stated above, the canned tunes are worthless.
How bad was the shortening of the frame? I have a similar project in the near future. Trying to decide if I want to cut the frame down myself, or take it somewhere. Are you going to keep it the factory color? Keep up the good work!
I love my CTS. I have installed 2 sets of isspros, in my old obs and my Superduty. It was nice to plug it into the obd2 on the 6.4 and be done with it. You would have to buy a pyrometer probe, I have one I need to sell if you are interested. It is the non expandable style.