i have a bmw z3 and i know that is the first part of my problem. i was in a ford focus with the 2 10 in type r's and it hit harder then my 1 15 type R . is the hatch back so much better then my trunk with the top down? if so will i just be wasting my money if i buy the 12 in x.x.x? i cant be the only guy trying to put some boom in one of these cars. please help