I was wondering the same thing. But as GM Tech pointed out it wouldnt hurt to add more vents and just close others to increase the air flow in the ones you need "now". If you do this vent mod posted above (block off the ends and cut foam/plastic) you will realized more air flow so IMO you could add TWO more and not even noitice a difference. This might be next on my mod list (Two more vents near the cockpit area). Im going to wait for the 100 deg days to come back to make up my mind.
I dont think I would add more than two anyway.
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