Since the Tru Boost controller has been more hassle than it's worth imo, I'm going to go back to letting the computer control the boost. My question is, since I had it professionally installed, what do I need to buy to have the computer control the boost again? I believe the controller I have now replaced a line or two but I'm not quite sure which ones.

You should be able to use the lines from the tru boost. Also most installers leave the original lines zip tied in the background somewhere.

I did the same thing, the tru-boost is now just a boost gauge and the computer is controlling everything.