That is a very nice temperature indeed! I must have done something wrong, or I have bad quality material. I did a mod as well but I still get 94 degrees after playing 20min of gaming. 80 while watching a movie.
mod -from the core to the backplate- : CoreM3=>MX something=>Copper shim=>Thermal Adhesive sticker=>OG heatsink=> Thermal pads all over the backplate=>CM+ backplate.
Should have done it your way but I thought mine would be more stable, with the tape instead of the grease..