Well to obtain 150DB you are gonna need alot of money and time for this, mattering on what kind of car or truck you have will determine that, 150 ain't easy to get to. First you need to figure out what car audio company you wanna go with, RE Audio, Fi Audio, DC audio, DD audio, AQ, Sundown Audio, Incriminator Audio, Ascendant Audio. I wouldn't suggest going to Rockford Fosgate since the most powerful sub they have is only 1200wrms, But Rockford Fosgate does make some really good amps. Second matters on your box size and the tuning of the box. The easiest cars to get loud are hatch back cars, trunk cars are hard to get loud but even harder if the seats don't fold down. Sound Deadener will help, and if you wanna go to the extreme you are gonna wanna try and stop all part of the car from flexing and letting pressure out.