Ahh, now I understand. Yes go with the "HK" one. Far easier and safer to install (and extremely puzzling that it's the cheaper!).
The non-HK one is the original GM kit. The "HK" one is CED's modded version with the connector adapters.
NOTE: you will still have to go to a dealer to have the ECM programmed with the coded program certificate that comes with the kit (that part is NOT DIY!). They will charge you for that programming, but shouldn't be more than an hour's labor (if it
is, move on to a different dealer - so get estimates first

)
This presupposes you put in the TMAP sensors yourself. Easy job, but you must drive VERY carefully until the ECM is programmed.
NO BOOST. If you get into boost, you will throw codes and go into limp mode, as the new TMAP sensor parameters don't match the old ECM program.