That "Vortec" writing on top of the air box is worth at least 5 horsepower, you guys know that right?
Haha, I've run it off and on with both my trucks and personally haven't noticed any difference, but I do like being able to get around the back of the engine a bit easier to access whatever/clean whatever. No ill-effects, I quite like the cleaner-looking engine compartment.
I'm going to have to take a vote against removing the air filter cover though.
My 2 cents.