Air filter surface area... + Maf ?'s

Im currently running a HCI mustang and have a shaved bay with a maf in the fender... my current filter is a tight fit at 5.5'' i want to cut down to a 4'' filter like this:
K&N RU-2990 - K&N Universal Performance Air Filters - Overview - SummitRacing.com

Will that be enough surface area? Dont know if it matters or not???

Also is to cool for my Maf to be on an angle... i know it shouldn't be after a bend

Yea i went with it for one reason... $12.00 on amazon

and it gives me a ton of room!