Conscript

I'd get the gearbox oil changed to something decent. Abbey put Millers gear oil in mine and that really improved the shifting feel. Shouldn't be too expensive, and can only help. 
Ask them to install MTEC shift springs too. They really make a difference to shift quality, they center the gearstick with more force which makes shifts across the centre of the gate easier and more precise. Perhaps what you're feeling is the stick catching on the gate slightly as you shift into third...before the shift springs if I shifted too quickly from 2nd to 3rd it was sometimes possible to stick on the gate between 1st and 3rd...the stronger MTEC springs help with that by applying a stronger centring force to the stick. 

Update for future reference: Lauren was right, it was the drop links. On inspection they looked fine, but as I had the car in the air anyway, I replaced them, and the noise has gone.
Surprised (and annoyed), as the old links looked and felt fine after removal...no splits in the boot that I can see, and they didn't feel too loose. I may cut the boots open later and check the rose joints.
And they are a pain in the arse to remove, even after only 6 months on the car. Still, preferable to having the strut assembly out. 

Getting back onto the topic of the actual start up screen, I've had a go at making one for myself. I wanted one in the same style as the OP, but with the Toyota logo instead of Subaru.
However, I then decided to add a little bit of flair. I just did a google search for "GT86 silhouette" and found a a beautiful outline image of the car posted by someone on Reddit years ago (so please, all credit to them as the original artist). I then also just searched for the Toyota logo on a black background and hey presto, manage to make what I think is a nice bootup screen
Hard to take a photo of it in car due to the amount of glare, so I've attached the files here as well as .bmp images, if anyone wants to use them. You can just use them with @Shad's .txt file, just ensure the image is named "image1.bmp" on the USB stick.
I believe this unit also supports custom wallpapers, so I might see if I can use the silhouette there as well.

image1-logo only.bmp
image1.bmp

Getting back onto the topic of the actual start up screen, I've had a go at making one for myself. I wanted one in the same style as the OP, but with the Toyota logo instead of Subaru.
However, I then decided to add a little bit of flair. I just did a google search for "GT86 silhouette" and found a a beautiful outline image of the car posted by someone on Reddit years ago (so please, all credit to them as the original artist). I then also just searched for the Toyota logo on a black background and hey presto, manage to make what I think is a nice bootup screen
Hard to take a photo of it in car due to the amount of glare, so I've attached the files here as well as .bmp images, if anyone wants to use them. You can just use them with @Shad's .txt file, just ensure the image is named "image1.bmp" on the USB stick.
I believe this unit also supports custom wallpapers, so I might see if I can use the silhouette there as well.

image1-logo only.bmp
image1.bmp

Yeah, I am going to neaten it all up later, try and tape everything that's needed away neatly and make sure nothing is rattling around. If that's the case, I'll plug the GPS in at the same time then. 
Initial impressions are good, though. Screen is nice and responsive, and once I'd grounded the handbrake wire, Android Auto setup was a breeze. The mounting bracket doesn't fit fantastically, but it might just need a little fettling. 

Congrats! Make sure you use plenty of loom tape on the wires to as not to create any more rattles
I connected the GPS antenna and fitted it inside the dash just above the stereo. In the BRZ there's a little box on a bracket in there to do with the alarm and it fitted along side that nicely. It only has plastic and glass above it so the signal is good. My understanding is that the antenna is used when navigating to save power on the phone, so I think it's worth hooking it up especially since it can be hidden away inside the dash.

Sorry, to be clear I believe the last I saw Samsung had fixed the One UI issue, so you ought to be ok now.
The automatic volume adjustment - you're right, it does not work unfortunately. I've also wired that up but it does nothing. Probably only a firmware update needed to enable it but having looked through said firmware trying to find other customisation hooks it's fairly complicated. I don't find myself adjusting the volume too much, unless I've been at speed and needed it turned up. But having not been able to drive much lately it hasn't really been an issue!

Hi Conscript, congrats on the 8020 purchase, I'm sure you'll enjoy it especially if you're coming from the stock head unit as I was. With the right fascia adapter (I used Connects2 CT23SU07 from Dynamic Sounds) and a bit of time and fettling you'll get a great fit. I was disappointed about not being able to get the WS unit here in the UK and didn't fancy risking buying one from overseas.
On the unit itself - the screen is capacitive and very sensitive, and the important physical volume buttons work very well. Wireless AA works very well with my OnePlus 5T although I've only used it when using navigation so far. I have a small USB stick for music in the glovebox. The Google Assistant works great or as well as it usually does with AA! I've positioned the microphone on the head lining just to the drivers side of the mirror which is usually fine but you have to raise your voice a bit if you're at speed because of the road noise in the car.
The UI of the headunit is a little dated compared to AA but it's functional and once you learn your way around it's fine. If you do listen to music on a USB stick and like to shuffle the whole thing then there's a bug in the software to be aware of. When you start the head unit after listening to tracks on random, the next track it plays will be the next track in its predecessors album, rather than an actual random next track. It sorts itself out after that, and you can skip to next as well. A very minor grievance on an otherwise excellent system.
These are all of the parts I used for my install:

Post or PM if you have any other questions...

Going by the videos I've watched, the DDX919WS is indeed wireless (long video here: 
However, as it needs to be imported from abroad, I've now ordered the DMX8020DABS, same as Shad. It doesn't look like quite the perfect fit that the DDX unit is, however, it looks nice and neat in his photo above, so I'm happy with that. 

It's not just cheap 95RON fuel. I've had the crickety fuel pump forever, and the car has been run on V-Power or Momemtum-99 almost exclusively - neither of which are cheap, nor 95RON. 
The only time it ever disappeared was when using Esso-97, which apparently how no ethanol. Now that Esso do a 99RON fuel to rival V-Power/Tesco Momentum, and my nearest fuel station is Esso, I've switched to using that. Since then, no crickets. 

Update for future reference: Lauren was right, it was the drop links. On inspection they looked fine, but as I had the car in the air anyway, I replaced them, and the noise has gone.
Surprised (and annoyed), as the old links looked and felt fine after removal...no splits in the boot that I can see, and they didn't feel too loose. I may cut the boots open later and check the rose joints.
And they are a pain in the arse to remove, even after only 6 months on the car. Still, preferable to having the strut assembly out. 

It's not just cheap 95RON fuel. I've had the crickety fuel pump forever, and the car has been run on V-Power or Momemtum-99 almost exclusively - neither of which are cheap, nor 95RON. 
The only time it ever disappeared was when using Esso-97, which apparently how no ethanol. Now that Esso do a 99RON fuel to rival V-Power/Tesco Momentum, and my nearest fuel station is Esso, I've switched to using that. Since then, no crickets. 

Thanks Lauren, that's good to hear, as I can check and change the links easily myself. The car has been checked twice since the link was installed (inspected after the recall and a video sent to me where they mentioned the drop links looking fine, funnily enough) and also went through the MOT. But if it's only a tiny split, then it could easily be missed. And the car has been driven in some torrential weather lately...so water ingress is likely I guess. 

I expect one of the boots on your drop links has been damaged whilst being installed. It got diabolical when turning, the creaking noise was just awful. But it was quiet otherwise. It was a tiny split in the boot on the offside where the rose joint bolted into the strut. No way could you see it really without removing it. Once it was off though you could see the rose joint had gone rusty. 

He's referring to Abbey, Fensport and Tuning Developments.

Consider Abbey Motorsport too, they're based at Oxted in Surrey, so even closer to you (under an hour from Basingstoke maybe?). Well regarded in this community, so worth contacting them for advice. Pretty sure you could buy the TD kit and have it fitted and tuned by Abbey if you don't want the 7 hour round trip. 

You could try this:
https://toyota.epc-data.com/86/zn6/
The specific diagram looks like it's here:
https://toyota.epc-data.com/86/zn6/183230/electric/8106/81735/
Click on the relevant part in the diagram and it should bring up the Toyota Part Number.
Edit: Took a screenshot of what I think it is....
 

Cross-posting from other forum...
Picked up the car today. Recall done, plus full service, spark plugs and a new clutch. Cant say the engine feels or sounds any different, perhaps a tad smoother.
New clutch feels good - same pedal weight, but engages a bit better now. I was convinced on the way home that something was wrong with it, but it was just a consequence of having just climbed out of the courtesy Yaris. They also tightened the handbrake a bit, which was handy. It had been a little slack since I did the rear bearings and I intended to take a look at it at some point, so that's one job I don't have to bother with now
No problems so far. I'll be driving up to my parents at Christmas, which is a couple of hundred miles, so that should highlight any issues.

Cross-posting from other forum...
Picked up the car today. Recall done, plus full service, spark plugs and a new clutch. Cant say the engine feels or sounds any different, perhaps a tad smoother.
New clutch feels good - same pedal weight, but engages a bit better now. I was convinced on the way home that something was wrong with it, but it was just a consequence of having just climbed out of the courtesy Yaris. They also tightened the handbrake a bit, which was handy. It had been a little slack since I did the rear bearings and I intended to take a look at it at some point, so that's one job I don't have to bother with now
No problems so far. I'll be driving up to my parents at Christmas, which is a couple of hundred miles, so that should highlight any issues.

You can unclip the top of the brake light and remove it if you unplug it from its connector in the boot. However, the legs can't be removed without taking out the whole shelf and drilling them off. But you are able to remove the shelf with them in place by bending it. 
There's a guy on the GT86 Drivers Club Facebook group who was selling a kit to lower the brake light (I assume he's on these forum too) and he made an excellent video showing you how to fit it, which includes detailed instructions for removing the shelf from the car...you just have to be a bit heavy handed and bend it a bit. But it's not going to snap and will return to shape fairly easily. And he shows you the approximate locations of the securing clips. 
https://youtu.be/aiCh61698pw

Finally phoned up and have got my car booked in to Beadles Medway on the 14th. 
Been a bit worried and had a few concerns, but the girl on the phone gave me the details of the service manager, so I sent him an email asking about including servicing, clutch, spark plugs, etc, as well as informing him about my modifications. I also thought I'd be blunt and ask about how many recalls they'd done due to the issues other owners have been having. He phoned me back within 30 minutes and we've just had a chat about it. They've done between 10-20 recalls he said, and so far, only a couple of cars have come back for minor oil leaks and such - no catastrophic failures for any cars they've worked on. Which has put my mind at ease a bit.
Should be getting a full service and new spark plugs at the same time. I've enquired about a clutch, but I am going to let him know, as I'm considering whether it's worth going for an aftermarket replacement. I don't plan of adding any more power, but I've been told putting in an Exedy clutch would be a good upgrade. Any opinions would be welcome - I don't want to do anything that will feel any different.

From Sunday morning... 

You'll be right at home with a GT86 then
Welcome to the club, enjoy

Well, I've just replaced the front bushes, and it seems to have cured the problem. Took it for a drive again, no unusual noises over speed cushions, nor when I manoeuvred while parking outside my house. 
Only issue (aside from it starting to rain while I was working) was that I managed to strip one of the bolts which holds the metal clip encasing the bush to the sway bar frame (the part which bolts to the chassis).Because the clip doesn't go down flush, as you're crushing the bush, I managed to cross thread the bolt and didn't notice until it was too late and I had a socket on it. Luckily I managed to find a similar size bolt and nut in the garage to replace it with, which seems to hold okay. If it doesn't, I'll have to find a replacement frame somewhere. But still, prat 😕
Can't say I've noticed any improvement in steering response, although I went with OEM drop links.

Almost a year on from this post and I never got around to fixing it myself. But last month I was looking into the problem again and found that they sell these little clips on Japan Parts, and they aren't charging 15 quid each. Instead, I was able to get 2 of them for 17 quid, delivered. Overnight parts from Japan, yo! 
Although not overnight. I ordered on the 19th May and they turned up this morning. That's a little job to attend to in my time off this week