Just some quick noodling (and boring math in Excel) but if the IAT could be reduced by 60F (from 150F to 90F) then you would see about a 9% increase in compressed air density in the chamber and a concurrent increase in fuel trim (richer) to compensate.
More likely would be a 20F drop from 120 to 100 & a 3% change. That plus a 15F reduction in coolant temp might give a 5% increase in charge density. I would not expect any more.
Things to monitor before and after are IAT, coolant temp, IMAP, short and long term fuel trim, throttle position, and load values for steady state. Really would need a dyno for accuracy but all are available on the OBD-II feed (all that is needed is a notebook/netbook/laptop and a $30 thingie from Amazon).
The HEMI CAI thread has a lot of good info but for me, I want to know the IAT as close to the throttle body as possible.