i have recently tried numerous set ups in my car and still not satisfied. originally i had 2 jl audio 12w3 in a custom sealed box in the spare tire well and decided to change it due to sloppy sound. before that i had one adire audio brahma 12 in a sealed and did not like it. so last week i got 2 MTX 9500 12's (weigh 50 lbs each) in a ported box with a MTX 1501D amp running them. the sound is awesome and very clean but now i do not have any room in the trunk with no spare tire. also, i have a cusco carbon rear strut brace that cannot be seen due to the large box. i want to change it one final time, but cannot create a custom set up where i could use my trunk like before (when i had the subs in the spare tire well) and not have to add alot of weight. i am thinking about just adding one 12 in the spare tire well and porting it or try to fit something firing back on top of the strut bar. my main objectives are to obtain as much spl i can (i mostly listen to rap)without adding alot of weight and at the same time leave space in my trunk for a spare tire or luggage. right now i have about 150-175 lbs in the trunk. any creative and helpful ideas will be appreciated.

 

Hi, I’m new to the board and just got an evo 2 weeks ago. I will be facing similar problems, as my main concern is to save weight. I was going to try a few 8''s about 3 maybe, I have not decided. Remember that 3 eights will cover the same surface diameter of two 12''.

Now they won't sound like 12''s but it may create the same spl... depending on many variants in your system. 8''s tend to need very little air space compliance and can sound very good above the 40hz rage being that they have a very high resonant frequency, which might be what your looking for, your post says you wanted a high spl.
Have you ever tried building your own box?

I am going to build one for these 8''. Usually you want to build a box out of 3.25'' mdf but to save weight I'm going to build it out of 1/2'' mdf and reinforce it with fiberglass to save weight. I have to go now; I hope my suggestions help you make a decision.

 

I did 3 tens in my car sounds great I used all JL audio subs amps and wires. Custom install looks great nothing too fancy but I still have about half my trunk left after 3 subs facing straight back and the 2 amps mounted vertically on the sides. total weight is about 60 pounds and without the spare I'm only adding 30 pounds.