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Nice DIY/build of the free air subwoofer and thanks for answering my question in the other post regarding the amp location.

Apologies for the long post :)

I am about to do the same exact install as you regarding the subwoofer, although I am going a little smaller. (Subwoofer Rockford Fosgate P2D2 - 8", AMP RF R500X1D 500Watt. Before I do that, I was thinking about upgrading the HU to an Eonon G7150.
You had mentioned in the other post that replacing the factory amp is also a big win, so I have a few more questions for you.

The audio upgrade plan is as follows:
1. Done. Replace all the BWW stock speakers with a BSW Stage #1. They sound much better than stock, but need more lower end, hence the subwoofer project.

2. In the works. Replace the BMW Business CD HU with a Eonon G7150 HU. This HU has 45 watts/channel, but I am not sure it will be enough. Using the supplied wiring harness adapter, I can hook into the BWM audio wiring harness. This will take the line outs to the factory amp, located in the driver side rear arm rest panel :).

Question #1 - leave the factory amp or get a new one?

3a. Leave the factory amp in place with all the current (npi) wiring in place to the speakers. Jump step #4 subwoofer install.

3b. If I were to replace the factory amp, what would I need to do besides, obviously getting a new 4 channel amp (4x100w should do it).

Question #2 - 4 channel amp recommendation to drive BSW Stage #1?

Wiring option #1: Use the provided wiring harness from the new HU to stock BMW wiring harness to the amp location. Then sort out the individual wires for each of the speaker locations to the amp. Then from the amp use the stock BWW wiring harness to the speakers.

Wiring option #2: (seems easiest): Run line out from the new HU via RCA to the new amp and then use the stock BMW wiring to the speakers

Wiring option #3: (seems the hardest) Run line out from the new HU via RCA to the new amp. Then wire each speaker with new wiring from the amp.

Question #3 - Which is the best/easiest wiring option?
Question #4 - I know that the factory amp has crossovers built into it. Do I need to do anything about the crossovers or can I run the speakers wire straight to the speakers?

4. Subwoofer Install - I planned on doing the same type of subwoofer install as you in the ski pass through. I am going to build a 5 sided box from MDF for the subwoofer with the back open to the trunk.

Question #5 - Is there any benefit to having a 5 sided box vs only having the subwoofer mounted on the one side with dynomat for the other sides?

Question #6 - MDF thickness 1/2" or 3/4"?

Thanks for your responses.
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