I was curious because it made sense to me. More air coming in-more air goin' out.
Took a 3/8" drill bit and drilled 9-holes on the back plastic outer plate. Fired it up and the little gun that would blew out more air and seemed to quicken my heatshrinks.
For the handy types in here that have a drill laying around and use a cheap heatgun, try it and I think you'll agree. You can use tape or vinyl tape about 1/4" up on the drillbit to keep it from going to far in and damaging the fan.
Good luck.

Try a unibit for drilling