Recently picked up 2010 S2 and wanted to update the stereo but wanted to the following features:

• Bluetooth
• SWC retention
• Android Auto/CarPlay a plus
• Easy Torque and Harry's Lap Timer access

I'm not super into audio and am not planning on better speakers or amps for dat-bass-yo so anything that could output to the stock speakers was fine by me audio wise. The last requirement of app integration was big and was what pushed me to go to a generic Android headunit rather than going with namebrands like Pioneer or Alpine. Existing namebrands seem to have a hard time mirroring Torque without a 3rd party app and that connection is also through Bluetooth which is mostly fine, but for gauges I wanted something that was always with the car and I didn't have to tinker with to connect. Harry's Lap Timer on the headunit was also nice (the headunit can display both apps via split screen which was an additional bonus) since on the track, fumbling with your phone is a pain.

Initial impressions:
Given it's a "no-name" Android headunit, longevity may be what comes back to haunt me but so far, this thing's been great. I have wired android auto (I think there's wireless Carplay for Apple people) and the 8's center console is pretty sweet for just throwing your phone in. Coming from a FD with no AC, simple luxuries like having cupholders and a storage space for your phone is honestly amazing. Also LOVE that the 8 has a plastic service plug in the cupholder area! I think it's for easily adjusting the parking brake but also let me run the short USB cables to somewhere hidden. Torque Pro came installed with the headunit and has worked flawlessly with my Bluetooth module BUT for some reason I can't seem to be able to download custom themes and the app can't talk out the alarm names (the alarm sound works, just not the text-to-speech). The unit itself boots up in a few seconds and while there's definitely some bloatware, it's fast, responsive, and the screen is 1024*600 IPS, which is actually much better than what midrange ($500) Pioneers come with. Audio is whatever, but the car came with a Invidia Q300 exhaust and I'm planning on throwing a BHR midpipe in it to save the cat so I don't imagine I'll really be able to tell the difference. Honestly, unless you're going to go through soundproofing the doors and interior, I don't see the point of high end receivers in a 2010 Mazda, it's not exactly a luxury car interior. The SWC of the Crutchfield harness and the headunit worked great, I retained all of the factory LCD functions, time, custom text, AC and ambient temp displays.

Installation and fitment:
There are a lot of threads on this so this isn't a walkthrough but there were a couple caveats with the install.
It's a 7 inch (supposedly standard 2 DIN) but doesn't quite fit in the Crutchfield replacement trim. The side plastic 2 DIN brackets that snap into the Metra 99-751 need to be Dremel'd a bit, otherwise the screws holding the 2 DIN brackets (made of metal) of the actual headunit don't have enough clearance to slide in. Not a big deal and for me, function (and budget) trump form.
The rear view camera install was also pretty straight forward. The camera sits on a bracket behind the license plate. The S2 seems to have a large hole above the license plate that you can run wire through and if you take off the trunk plastic piece, there is a rubber plug toward the driver side that can be popped out to run the wire into the trunk. I cut a X in it and ran the RCA cables through so it's kind of like a grommet and the rest is straight forward (T'd into the reverse light + and - for camera power and routed the cable through the center console to the head unit).

The headunit:
: $269 on Amazon
: $39 on Amazon - Just went with whatever was listed as compatible with the headunit. Could have probably went with something cheaper

Installation accessories:
$60 on Amazon - I could have went cheaper here but wanted something that, again, I didn't have to connect/reconnect if the bluetooth was spotty
Metra 99-7515 Dash Kit: $30 on Crutchfield
PAC RP4-MZ11 Wiring Interface: $110 on Crutchfield

Pictures of the thing:

Rear view camera

Customized home screen (via Nova Home Launcher App)

Fitment is definitely not 100%

Torque app works great. Look at that intake air temp even a couple hours after driving!

Harry's boots up fine, will have to see if it does ok with the headunits GPS antennae I installed under the center speaker cover.

Wired USB connection for Android Auto and a external USB storage device

 

Oh, for those that go with this particular headunit. The PAC RP4-MZ11 Wiring Interface came with RCA cables but the connections on the back of the headunit are for amp outputs. Took me forever to realize why the audio was so damn quiet. I wanted to finish the install so just cut the RCA ends from the wiring harness and spliced the individual wires with the direct speaker outputs from headunit.

 

Thanks for sharing. I have an ATOTO in my truck that's been good for a year or so. It definitely has its quirks and the polish of the name brand head units isn't there, but all I really wanted was CarPlay and a front/rear camera so this thing fit the bill great.