Custom Sub Q's

I own a 96' 3000GT and i want to put a L7 solobaric sub in the trunk, the only problem is that the trunk is very small and i think that i want to customize but i really dont even know where to start. I realize that i will probably have to lose the spare so i can place the sub in the trunk facing up, which is what i want to do. Has anyone done this or know a site that will show me how, or will i have to take it to an audio place? One other question, i blew a tweeter and replaced both of them, now i always here a buzz noise whenever the car is one, radio on or off. When i rev the engine the noise gets louder. Is it a bad ground, have i done something wrong?

probably a bad ground wire, check all wires

sounds like a bad ground, or you have cheap rcas and are running them next to the power