Sorry, I mounted it with 3M automotive tape and bolted the wood down with one of the threaded studs in the back cavity to give it better hold.

Nice job on the enclosure. I like the way it sits... Is there a grille for the sub?

What is the maximum depth if anyone knows off hand for the Spare Tire to top of foam for a custom enclosure on a BASE 370z since my spare is diff than the OP. I'm in the process of Fiberglassing an enclosure that sits in the Spare, and is flush with the foam board w/ carpet. However having a tough time getting an accurate measurement for the depth of the sub that I would need to buy. I'm leaning to a Polk DB Shallow Mount or a RF Shallow 12" or something like that. Advice is welcome. Thanks. and to the OP nice job on the MDF creation.

I have a Nismo also so I can't give you exactly what you want. But for my enclosure I laid a level across the foam piece and measured down from there to the spare tire. Measure the carpet separately.

Difference in base spare and Enkei
 

Osirus, the difference in wheel backspacing between Enkei wheel in OPs post and the steel base wheel is 1.18". That gives extra depth for speaker and larger volume for enclosure.

Nice work. I am liking the amp install location. And you have a PM!

Thanks for that, which means in total, I'm looking at 5 1/4" to 5 1/2" in total depth from foam to bottom of the backspacing metal of the spare. I think this project will come out fantastic. Shouts out to DIY section for ideas.

sub box
 

hello can you built me one of the sub boxes? PM PLEASE.

I went with an 8" sub and couldn't be happier. Did the backup camera and dynamat at the same time so my whole system is now complete. Thanks for the inspiration!

Did you end up cutting your stock carpet? If so, have any pics of how it turned out?

That turned out great,congratulations. I didnt cut my carpet, I just covered it up. When I built my box I recessed it 3/4" into the box to allow travel of the sub.

I love this idea but my concern here is; you're saving the spare tire right? But if you need the tire for a flat to have to take the whole sub apart to get to the tire. Seems terribly inconvenient when on the side of the road. Our is it for resale value?

Resale value, save trunk space, stock look, plus it's damn sexy imo. It's only 6 screws to get the sub out and Nissan provides you with a screwdriver with your jack & tow hook. It's way more of a pain to get the car jacked up and the tire swapped out on the side of the car than to stand behind it and undo a couple screws.