Ok, I finally figured out how to do inline photos..

The proper furnace-to-coil transition is on order.

Apparently the Skuttle 55UD underduct humidifier we were planning to put on the supply just barely won't fit, so they're going to use an Aprilaire 600 on the return plenum instead. Any thoughts on this?

Basement return into side of return air 90 elbow. Is this OK? Note that there are no turning vanes in the elbow and its centerline radius is less than 1.5 times the width of its cheek.. not sure how turning vanes would have affected the airflow with that extra return joining on the side anyway.

Gap between filter and filter cabinet. The media cabinet Carrier includes with Infinity furnaces doesn't seem very sturdily built, BTW.

Dust tracks on inside of filter cabinet door. Is this clear evidence of blowby? There's also dusty crud in the brand new condensate drain line, haven't actually taken the door off and looked at the coil.

Furnace venting. Looks good to me.. hope they're not planning on running that type NM cable all the way outside, and I'm not sure where the humidifier drain is going to go on that piping - guess I'll see tomorrow.