Thank you!!! I hear this all the time at the shop and after I say it most likely won't be the same they go out and do it and come back asking why is that guy louder. Even in the same model car, year and everything it most likely won't sound the same.winkychevelle brought up a very good point. Different vehicles will make the same equipment sound very differently (due to wave reflection/interaction, different resonant freqs, etc). So you can imagine how hard it is to compare different equipment in different vehicles... almost impossible to make fair comparisons.