I currently have 4 cube after all displacement with 43.75 sq/in of port fireimg down the middle tune @35hz. I was told that offsetting a port to any Side would raise enclosure efficiecy And get louder.how true is this? my new plan is 3.8 cube with 50sq/in of port tune @32hz with the port off set. sub are fi btl12 n2 with the mmats hd4000.05 and dc xp 270 alt x3100 in the rear xs2700 up front in a 03 impreza sealed off from the trunck.

Location of the port will not change enclosure efficiency. It will load the cabin different, and that may give you an increase (or decrease) in output.

Assuming the box will have an "L" port for tuning that low, then yes there could be an issue if one sub's rear wave hits the port wall and the other doesn't. Can cause uneven loading on the subs which could hurt output/efficiency.

Loudest trunk cars are using port in the middle, usually an external aero...

Edited March 6, 201213 yr by mlstrass

probably wouldnt notice to the ear, maybe on the meter changing from passenger side to driver side though.

like mlstrass said, typically when you seal off from the trunk usually does better and easier setting the enclosure back a little and running 1 or 2 external aeros.

Louder with a lower tuning for those btl's?

If you want efficiency I don't think you should lower the net volume.

I went from 2.1ft3 @ 32hz to 2.5ft3 @ 34hz and It is really louder to the ear. I still have the lows ! But I changed the port. It was firing to the side and now it is firing up like the sub.

Good luck

I would almost double that port area for sure...

I know with my single BL 12, 50 sq in works great and those BTL N2's displace even more air.