From: 2 15" fi bl's or 1 18" btl for daily on 3kw

hey everyone i'm looking to make an upgrade. i currently have 3 12's a crunch gp3000d pro amp which is suppose to be underrated at 3kw rms at 1ohm. i also have 0 gauge wiring a 300 amp alt fatmat throughout the entire vehicles i think two layers in some place but atleast one layer throughout the entire vehicle. i have an optima red top under the hood and a kinetic hc1800 in the back for the subs. i have a 1997 ford explorer sport (2 door) and i am interested in either 2 fi btl's 15's or 1 fi btl 18 n2 model i have enough space to run the 2 15's or the single 18 with no problem now my question is which would give more output. i love lows so im looking to have the box tuned around 30-32hz. both speaker options i'm looking at would be fully loaded. i read in the tech section that if you have less than 2000kw with the cooling option then the bl's are the right choice. so with 2 of them my 3kw should be fine and not push them too much. and we all know the btl's fully loaded can take sum serious wattage so im sure the fully loaded btl 18 could take my 3000kw. i really am looking forward to suggestion by people who have had experience with both or official fi audio support i think i gave a thorough explanation of what im looking for and what i have but feel free to ask me more questions if it helps your suggestions

i'd also like sugguestions on whether to use the 3 or 4 inch coil options if you think the bl's would work better for my system im also considering at an xs d3100 batter to my set up also with either speaker choice thanks in advance for your help everyone