There really only are two radiator options from what I see and have experienced. Supermiata CSF Crossflow for light and oem fit or TSE for biggest you can fit. I am really fond of the Supermeowta Crossflow. It is fucking light, looks high quality, fits like oem and kept my msm with undertray and stock fans at normal temps. But now I am adding power I switched to the TSE. Well the price is fairly spread apart between the two $619 and $402, with the TSE needing a aftermarket fan in some cases like mine.. Both are equally baller. But I think they both have their place. The Supermiata Radiator is nearly as small as OEM as far as space it takes up and stock fans bolt up, while the TSE takes up alot more room and will only allow one single oem fan(not w/ RB Sway brace) or slim spal. The supermiata has two drain plugs, which at first seemed handy, but in reality it is two more leak points, where as the TSE has no drain plug(kinda a pain) But no worries to be had. My Supermiata Rad. leaked from both drain pliugs just after a couple drains due to the oring failing, the plugs got to the point no o-ring would seal and I opted for a crush washer, which didn't work. I ended up using a high tack sealant to permanently seal the plugs as I could not get them to stop a slight constant drip. When I opened the box for my TSE radiator I was immediately in shock as to how fucking big it is...lol It is massive, and weighs a bit more than the super. But there is no doubt in my mind I upgraded further from the super. I now have one single 14" spal, no drain plugs to leak, larger cap and throat with a sacrificial anode.If you need room for stock or shrouded fans, IC tubing or want the lightest weight baller radiator, go Super. If you want the extra margin of cooling efficiency and don't worry about space, oem fans(ac) or weight. Go TSE

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Reroute kit was out of stock on the Supermiata website when I first placed my order, so I went through FM, not realizing they were backordered too. By the time I realized it, Supermiata had them back in stock, so I ordered through there and got it in two days (thanks Emilio!).
I was getting some boiling a couple weeks ago, so I topped off the coolant and was sure to burp the system really well. I also did a simple length of aluminum tape on the top front edge of the radiator. On the hottest days I still had a little boiling happening, but just a few drops. I have a 1.1bar cap of unknown age, but figured I would just be careful until I got the new radiator and reroute installed.
I hooked up a scan tool this morning to keep an eye on temps. Ambient was ~59F, and doing about 83mph for a 20-minute stretch resulted in ~214F according to the scan tool.
The plan is to get the new radiator and reroute installed tomorrow, and do some ducting at that point to seal up the front of the radiator all the way around. My condenser is not in great shape, and I hit a lot of bugs on my drive to work each day, so it might be easier to just replace it rather than clean it, and try to add some sort of open mesh to mouth the to catch the bigger bugs - but I'll hold off on that for now until I get data for the new radiator/reroute/shrouding. At this point I'm certain the new setup will make a world of difference (especially the ducting - coolant temp seems to rise fairly linearly with speed from what I saw today).

Please remove mystery meat rad cap. Rad caps are a wear item. More than once, I have seen expensive engines done in by failed caps. Cap has two seals. The secondary seal (outer) is the important one. It allows excess pressure to push coolant in to the reservoir. The key is it will allow a vacuum to build in the system which draws coolant in from the overflow tank. If this seal is bad, no vacuum will build when the engine cools down. So on every heat cycle, some coolant is pushed into the overflow res where it evaporates instead of being sucked back into the system. Your coolant level gradually drops until
you have a massive air bubble, which inevitably reaches the head. When it does, it'll pop a head gasket in a few seconds. You'll see the temp gauge spike and 3 sec later a plume of coolant vapor in rear view mirror.

Inspect the seals on the cap regularly. Also make sure your overflow tank is seeing two way flow when hot and cold. Another reason to install a coolant pressure gauge on your track car BTW.

OEM is 1.1 bar. Koyo cap is 1.3 bar.
Our Crossflow ships with a 1.4 bar cap and is also available separately.
https://supermiata.com/CSF-radiator-cap-4540.aspx

I just have to make it home today - next time I drive the car will be with your crossflow radiator and included cap :)

And what is the price for a SuperMiata radiator cap from 949 Racing?
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Okay, new radiator is installed, as well as the reroute kit. It went fairly smoothly, unsurprisingly the trickiest part was working between the firewall and back of the head, but not too terrible. I ended up moving the condenser to the front of its mounting brackets on both sides.

The bleed has been a bit tricky... I cold bled it through the bleed fitting as the manual suggested, until I had a steady stream of water with no bubbles. I burped the upper radiator hose when I did that. I closed it up and then hot bled it using the Lisle funnel suggested in the instructions, with the car level (not nose up). It seemed to keep getting an air pocket in the new thermostat housing, because the gauge on the dash was reading the temp accurately as it warmed up, then it started reading full cold. Radiator got nice and hot, but fan didn't kick on due to the air around the sensor. Even after opening the bleed plug while hot (until dash gauge started showing warm again), it seemed that the air pocket would return to the thermostat housing.

I'm planning to drain the coolant once it cools off (this was just a water fill to flush most of the old coolant out). Should a nose-up fill/cold bleed/hot bleed do the trick this time? Any other suggestions?

Before going crazy over bleeding properly, check that the gauge sensor is grounding properly, as it grounds through its' body to the engine.

I will check that out, but there was definitely air in the housing when I opened the bleed screw hot, and once I got the air out, the gauge came back to life (tried this a couple times).

Okay, good call. I ran a jumper wire from the sensor body to the intake manifold while a helper watched the gauge, and it jumped up. Now to figure out how to ground it permanently...

Not super happy with my grounding strategy, but I think it will hold up okay. I wove some stripped wire through the slots in a hose clamp, then clamped it around the hex fitting of the sensor. Put a spade connector on the other end and routed it to the ground bolt on the throttle body. Did a super thorough bleed with the nose in the air (couple of mild heat cycles).

I did some temporary ducting of the radiator, just the top and bottom sides, using aluminum tape. Started making templates for a permanent solution with cardboard, but I need to go buy some aluminum or plastic or something for the permanent pieces.

I live on top of a ~500ft tall hill, as I left the driveway, temp read ~165. By the time I coasted to the bottom of the hill, temp dropped to 150 lol. Drove about 3 miles at 70mph, temp got up to ~190 and seemed to stabilize. Going back up the hill at 25mph (5-12% gradient for 1.5 miles), got to 195, and then idling in the driveway it gradually climbes to 205. Then the fan turned on, and dropped it back down to 197 before it turned off. No signs of leakage so far, and the system built up a little pressure. We'll see how it does on the commute tomorrow.

NB1&2 gauge sensor is a 3 wire. Power, signal ground. Grounded through the OEM harness. Consult FSM wiring diagram or poke it with a VOM if you have doubts.

If you have anomalous gauge readings, it has nothing to do with the Qmax.

Yeah I just checked the factory service manual, I see that it grounds to a signal ground pin on the ECU ("4O"). I'll do some investigating tomorrow and try to see what's going on, but I think my bandaid fix will get me to work tomorrow.
The reroute and radiator seem to be of fantastic quality, and fitment is pretty darn good. If you want any feedback, I noticed a couple of things that might be helpful to add to the instructions (a few steps I took weren't metioned in the instructions, but it would have been next to impossible to do the install without it - e.g. removing the EGR tube was required to get the old housing clear of the stud).

The gauge half of the NB CLT sensor is not grounded through the harness. It's grounded through the body of the sensor, as HarryB said.

Ah, that makes sense now. I'm guessing that the sealant and/or anodizing is responsible for the insulation of the sensor body. The easy solution probably would have been to sand down the anodized coating from the sensor area of the housing and under a bolt head, but I don't feel like draining and pulling it out...

Anyway, car is running cooler for sure. Last drive to work (Friday), I was at 212-215F with 59F ambient temp. Today with the radiator and reroute, and only top surface sealed off (bottom blew away), 190-192F with 62F ambient. It held dead steady at those temps for 50+ miles at 80-83mph. It should be 92F ambient and sunny this afternoon when I head home, so that will be the true test. I'm sure with halfway decent ducting, I'll never have an issue. Very happy.

EGR tube is too cozy with heater hose, popped a small hole in the heater hose this morning. The straight barb fitting for the heater hose points it towards EGR tube, and there's not much room to route the heater hose differently. Perhaps a 45deg hose barb would do the trick.

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EGR delete anyone?

Or bend the tube. Aren't they fairly ductile?

I vote mallet.

Rubber doesn't like that kind of heat, also.