All,

I noticed there is a lot of discussion/debate around whether to tap the preamp bose signals or line level into your sub amp. In a lot of cases it depends on whether your amp can accept balanced signal input (which the Bose HU sends). Most high end amps can, including mine: Alpine MRV-M500 V-Power 500W Class-D Digital Monoblock Amplifier

Long story short, I tapped my preamp rear speaker lines and the sound quality is superb. I've run high end aftermarket headunits in the past and this is absolutely on par with those. I'm running a 12" alpine bass line sub (250w @ 4 ohms) in a custom fiberglass box that I made. The sub is a great value and sounds very good in a 1-1.5 ft sealed enclosure. Gets plenty loud and is very musical.

Just for testing purposes, I also tried tapping the speaker level wires and the sound quality was significantly worse. The bass didn't blend in nearly as well and I would have to adjust the EQ from song to song.

So, for anyone thinking of installing a sub in the back, I highly recommend going with a balanced signal compatible amp (like mine) and tapping your wires accordingly. And definitely, definitely solder your splice connections. It is quite awkward soldering in that position in the trunk, but it will ensure a strong clean connection.

I'm not 100% happy with the carpet color match, but oh well. BTW it is a real pain stretching carpet over such a contoured shape. I recommend using contact cement in tandem with hot glue.

EDITED: PICTURES ADDED

 

any pictures of the fiberglass box?

 

Pictures of box and a quick shot of the wiring