I need some advice on whether to go with 2 btl 15s or 2 btl 18s. I have about 16 cubic ft of space to put a box in my car. I will post pics of the car asap. I am just looking a system that hits hard hopefully around 148 to 150 dbs.

Let's forget the possible measured db output for now. You need to provide a great deal more info on you goals and system. You need to explain if that is 16 cubes total, as in before port and driver displacement?

I bring that up because in a system that what I guess you are going for, is that it would be better to use the smaller driver in a proper box, then a larger driver in a box to small for it.

i think your goal is more than realistic with 2 15" BTL's

But we need more info to help

Let's forget the possible measured db output for now. You need to provide a great deal more info on you goals and system. You need to explain if that is 16 cubes total, as in before port and driver displacement?

I bring that up because in a system that what I guess you are going for, is that it would be better to use the smaller driver in a proper box, then a larger driver in a box to small for it.

Okay sorry for the lack of info kinda new to posting well this is what I currently have.

1 RF 2500 amp

all 0/1 kicker wiring

190 amp alternator (not currently using will instal after finish putting in my turbo this weekend)

2 kinetik hc1400 batteries and 1 optima yellow top under the hood

Stock Bose component speakers and deck (using an mtx-req)

More specific on the goals I am considering entering a competition in october running in the 0-1000 watt modified class so im not aiming for sound quality. Even though i already have a rockford amp I most likely will buy a dd M4. A few friends of mine told to run dd 9500 15s however I want to try running with fi btls. I can build a wall which will contain a total volume of 18.4 cu ft, after measuring in 3/4 for the wood and 200 sq in port and 2 18'' subs the total after all displacement is 13.95 cu ft hope this is enough details thanks for all the help...