So I have a 2006 Coupe S and I already replaced all of my door speakers with the Infinity Reference line, and added dynamat to all the usual areas. I also used spray foam to fill in the wheel well areas for the rear speakers, which I think helped alot! The rear speakers sound really great, I think some sort enclosure would help the front speakers, but I gave up on that for now. I mounted my amp underneath the passenger side seat which has worked out perfectly. I have stuck with the Stock HU for now, but will upgrade that down the road. I will post some pics of the amp install, but due to the time it took, I did not take pics of the rest of the process.

Hopefully this weekend I will install my subwoofer and amp. I am building a box like another guy on here did to fit in the well in the back. Unfortunately and fortunately that is where my battery is located, so I plan on mounting hinges to the speaker box for easy access to the battery when need be. But wiring my amp will be much easier, with the battery right below it! I have a JL 10W6 that I will be building a box for.

I already found from JL's website that the sub needs about 1.03125 gross cubic feet or .644531 net, taking in to consideration the size of the speaker. The box for the speaker will need to be 21.75" wide by 13.25" deep and 5.75" high. This will make the exact volume of 1.03125 cubic feet for the speaker. The mounting depth of the speaker is 4.875 inches, and using .625 inch particle board, a height of 5.75" will give me .25 inches of clearance for the subwoofer magnet.

I figured there is about 6" from the floor of the trunk to the lip of the trunk, so it should sit almost flush once built. Depending on the physical size of my amp will determine where I put it, which is my biggest issue now, because I want the sub centered. I am getting the amp and speaker from my brother in law tonight so I do not know the exact size of the amp yet, but hopefully it all falls in to line with the plan. I will post pics of the box and install for others to see. I dont see the box costing much to make other than time, and whatever material I cover it in. Once it is all done, I will plan on making a nice MINI logo using the grill cover, I have yet to decide if I will build a cover or not, since I would like to keep it as streamline as possible, so my trunk can be used like normal. I am thinking about setting the sub slightly lower in the box so it sits a little lower than flush, so that the grill cover is about flush as well.

Will keep you updated!