Just wondering, if I drive for a long road trip w/ the cover off the stock intake will the S make better mpg cruising at around 75?

I believe I read a slight performance increase up high but off-set by down low w/ the cover off.

Mileage isn't the most important thing, but if I'm just cruising, why not? (Not driving in a dust storm, rains, and I don't mind it louder).

 

becareful of heat soak. lol when i take of the stock box my MPG goes down beacuse the sound makes me want to floor it more

 

NO, sorry with the lid off, you can only getting hotter air, unless you have a vented hood that have a opening directly above the box(which is not very smart consider the rain)

get a snorkel and keep the lid on, the only thing you get without the lid is the ricer intake noise