this weekend i shall be removing a complete S/C system off of a 07 cobaly so i can put it on my 05 cavi. Been reading up on the removal process and everythign seems straight forward but one thing...In order to remove the intake manifold it says i need to drain and remove the A/C system...this true? or can i just leave it in?

Also what other things should i get asides from the system off the car for the install...already gonna get:|
-S/C
-manifold
-H/E Pump n bracket
-tensioner assembly
-idler assembly
-alternator n bracket
-H/E tubes and resiviour
-brake booster line
-serp belt
-bolts