Best port configuration for 1998 3000gt?

[Kevin M]

As it says I have a build starting on my brothers car in a week or two. We're going to put 10 speakers in and he is going to use a Re sxx15" d2 for his substage. It requires 4 cu. feet and we have the room. I wanted to do an aero but according to the website I need a 12" which is a no go for vertical mount. I wasn't sure firing back would'nt work due to there being no area for the port to unload. Would a slot port be easier? Should it fire up along with the sub? Need a little experienced advice here. I don't want to build till I find out.

[Kevin M]

Here are a few pictures of the car. I need ideas guys.