Once again 92 d15b vtec

The last time I ordered headers, it was for my 67 Camaro. Hookers Header and in pairs. Now that I'm in the Import scene, I ordered a Megan Stainless Steal header. I did a search and didn't come up w/ much. A guy with a Lude saw his temp go up, but saw an overall drop in temp under the hood, as well as a an increase in the efficiency in is A/C.

Can anyone explain the do's and/or don'ts - the gains and/or losses due to wraping your headers w/ thermo wrap?