Bazooka Placement Questions

[MJS]

I have a couple of Bazooka amplified bass tube placement questions which will help me decide which one to buy. I could fit an 8" tube under the front dash on the passenger side, but both ends of the tube would be touching or nearly touching a hard plastic surface. Would this ruin the sound quality?

Do your amplified tube subwoofers need to be bolted/screwed securely to a metal part of the car? Would they still sound good if securely cradled in soft material (to prevent vibration noise) as long as the speaker was facing a hard surface?

Thanks.