need box design for alpine type r 15

trust me, changing the port from 3.5" to 5" wont do anything for port noise. 3.5 is about the same i use for the port for the box for my 18SX. adding port area will only increase your port length while trying to keep a similar port tuning frequency. 3.5 X 13.5 is still a HUGE port for that sub. mine is only 3 x 18 x 28ish and i get NO port noise that i can detect

oo ok thanks alot guys !