I have a 2008 4-door (TGN26R). Regarding speaker/radio upgrade, if budget allows, I would recommend the following:
- Replace the head unit (use Toyota spacers to convert standard double din unit to fit the dash). My JVC KW-AVX640 Head Unit cost US$268 in 2011, is old now but still works like a charm, including the blue tooth attachment. Much better are available for less these days, including android units. Of course there are also higher end double din units for more. This allowed me to add a cheap backup camera. I recommend the higher end cameras.
- Replace all door speakers - I used Pioneer TS-A1685R 6-1/2" / 6-3/4" 4-Way TS Series Coaxial Speakers (US$46.3/pair on Amazon) (stock speaker cut out and it's frame used as the door basket). The speaker's centre tweeters pushed slightly against the door panel that covers it, but no issues from that.
- Install flat sub in custom MDF box behind rear seat. I used the Pioneer TS-SW2501S4 10-Inch Step Up Shallow S4 Subwoofer ($US91). Installed since 2012 and still pounding away.
Custom MDF box dimensions: width 30"; Height 12.5"; Inner depth at Bottom 5.5"; Inner depth at Top 3.5"; Speaker cutout 9.25"; Cutout as close to the bottom as the speaker would allow - about 2". This gave a tight fit that pressed a bit against the back seat with the speaker protective grille in place. I recommend you take your own measurements, but make the box as wide as possible leaving space for the amplifier to stand against the back wall of cab. The speaker box restricts lifting of the seat but still allows access to the storage boxes below.
Install additional tweeters in rear doors to even out high-end. I used Alpine SPR-10TW 1-inch Silk Ring Dome Car Audio Component Tweeters (US$70/Pair on Amazon) in the back doors and maintained the stock tweeters in the front door. They new tweeters came with crossovers.
Power it all with a power amp installed beside the sub box behind the rear seat. I used a POWER ACOUSTIK GT5-2500 Gothic Five Channel Amplifier (US$127 on Amazon). Newer available.
look for newer and improved versions to all that I have listed above, as this was done a few years ago. An excellent website is
http://www.crutchfield.com and of course Amazon.com.
I hope this info is useful.