I just used the extra acoustic foam in the pipes (outside) because it looks better. And I have of course the foam inside each pipe.
Temperature in the room is okay. And in fact pipes are 6 inchs.
The fan doesn't seem to be connected to the pipe. It has to be airtight, otherwise hot air will get into your intake.
Also - if you put that thick eggcrate foam inside your 6 inch pipe then what's the actual usable inside diameter? ~2"?