xxx15 box tuning

im working on box plans for a 15 xxx right now the most i can fit into my trunk is 3.2 cu.ft. what should i tune at a firend who has a similar set up told me to tune at 32 hz but i was thinking somewhere in the area of 27-28 hz also should i use a slot port or a 4 inch aero port
box is going in a 94 mustang gt

i would tune 28 hz with a slot port.

whoah woah woah. A single 4" port isnt even enough for an old XXX 15. i hope you arent getting a new XXX.

what size port do reccomend cb this is the old xxx dont have the 600+ for the new 1

40-50sqin of port area for a slot port, can get away with slightly less for a round/aero port. 2 4" would be the minimum, 3 would be best.