Ok here is a real product review on the Audiobahn Alum Q series subs. The Alums are the "SQ" sub from audiobahn. These are some descent subs for the money. Unlike just about every other sub made by audiobahn these are meant to run in sealed enclosures. Their sound quality is good when in stalled right and the when the amp isn't clipping like a madman. In most of my installs i reccommended putting the hpf at around 80 or so and a sub sonic filter at around 25 ish or as close to that as possible. The response is great hitting the notes that are supposed to hit. These subs aren't meant for Deep low nose tickling bass but still put out some volume. If you listen to alot of music with guitars or even songs with alot of beat these are good. However, these subs aren't meant for bass cd's. They can hit the notes but they aren't as good as most other audiobahn brand subs.