Ok, I'm trying to reduce noise, so I don't think this is a DIY violation.

Everyone here has been helping me with my newly installed Carrier 38HDR
and Carrier Performance 80 recent install. A small 887 sq. ft. condo with
the furnace closet placed in the hallway near living room. Plenty adequate
return which basically below that same closet. The issue was the limiting
the noise from such a setup as having a furnace closet practically in your
lap.

Anyways..I have managed to reduce the sound significantly by lining the return cavity under the closet with 2" fiber material. That helped tremendously.
Besides the plenum board that they lined the closet walls with, I added closed
foam fire retardant sound absorbing/blocking foam. That helped a lot too!

My living room register box was so damn damn close to the plenum, I extended the flex duct by going back and making a gentle U-turn back to
that LR register box. That helped tremendously quiet without dropping air flow that much at all.

Now on to my question, I used Dynamat on both sides of the exterior furnace wall panels and also on the front panel, even on the evaporator coil box.
That has absorbed significant noise sound from Carriers blower motor.

Is that Dynamat on the side panels of the furnace going to cause any problem? As I understand it, the side panel of todays furnaces get no
hottter than 120F which the Dynamat is supposed to handle, seeing as
Dynamat is used in cars which can get up to 140F (windows closed, hot day)

I can always peel it off if you guys recommend I do so.

Thanks.