I'll come and edit this page in the future when more time permits.
DETAILS and a template to come!
I put some big 6.5 inch drivers in my doors using custom "build-outs" that I made.
NO cutting of the door metal was needed and I used a old set of door panels for this speaker upgrade (Still have a real clean set of uncut stock ones :P)
I used two layers of 3.4 inch MDF from LOWES ($6.00 for one board found in the kitchen upgrade area)
I also used 1 yard of Black Vinyl ($7.00 at a local fabric shop - they had blue,navy,grey,brown and red)
I also used real short (1.25 inch) drywall screws, 3M spray adhesive and lots of time creating a template that would NOT require cutting the firewall.
I wrapped each layer of wood with the vinyl (spray adhesive and a heavy duty stapler) after cutting the speaker holes then stapled in the XTC pods after I screwed the two layers together. I then attached the pods to the door panel (after cutting speaker holes) using the drywall screws installed from the rear.
The Speaker location may not be the best for perfect imaging but with a total of 150 real world RMS watts powering my Mids and tweeters I SOUNDS AWESOME and LOUD!
My speakers are -
Goldwood 6.5 inch woofers from Partsexpress.com ($24.00 for the NEW pair) Profile dome tweeters ($10 new on eBay :P) Alpine 2-way adjustable Crossovers (from a friend $20) XTC speaker protectors - Crutchfield.com ($16.00?)
I was told by a local Hi-Fi shop owner that builds custom speakers that Goldwood's would give me the same performance as the JL audio's and the Polk speakers I was looking at for about $130 cheaper (sans grills and x-overs).
AND they DO!!!
My brother has some Polks in his Miata and they sound like POOP next to my car!
But I do hope this helps!