I would swap it now for peace of mind since you will be taking it to the track on occasion. The factory radiators are more then efficient.
I ran a Mishimoto for a while and it kept temps at 180 pretty much all of the time. My fans rarely ever turned on, and it was always in traffic on 100 degree days when it did. Only took a few seconds to cool down too. Ended up going back to stock because 3rd gear pulls would drop my temp between 174-176, and that's a slow 3rd gear pull since I have an auto trans. Unless you plan on boosting, I think it's overkill.

 

I would swap it now for peace of mind since you will be taking it to the track on occasion. The factory radiators are more then efficient.
I ran a Mishimoto for a while and it kept temps at 180 pretty much all of the time. My fans rarely ever turned on, and it was always in traffic on 100 degree days when it did. Only took a few seconds to cool down too. Ended up going back to stock because 3rd gear pulls would drop my temp between 174-176, and that's a slow 3rd gear pull since I have an auto trans. Unless you plan on boosting, I think it's overkill.

Are you implying that it actually cooled the engine too much? Is there a risk from temps dropping too low? I have a 6-speed type-S, mostly stock engine. This car also needs to be daily drivable as it is being switched to (primarily) DD duty with backup as track car.

It looks like the aftermarket ones are actually cheaper than OEM, so if it should be replaced is there any downside to just getting the mishimoto?

 

It sounds like the issue you mentioned (over-cooling) should only occur if the thermostat is not working properly:

https://mechanics.stackexchange.com/questions/430/can-radiator-cool-down-a-car-too-much#:~:text=It%20100%20percent%20doesn't,cooler%20coolant%20from%20the%20radiator

.

is that right?

 

In my experience, it was cooling too much. Took forever to dial in my a/f ratio because of it. My thermostat works fine, it’s just that the aluminum rads are more efficient at cooling, and they hold a little bit more coolant. The factory one will lower my temp too, just not that low.
Is it bad? Probably not, but I was always taught to not romp on an engine unless it’s at operating temp. You type s guys also have an oil cooler pipe that runs through your water pump, that’s what I’d be more concerned with.

 

I ended up getting the koyorad, happy with it so far and does not appear to be over-cooling. Worth noting that there is a very prolific company selling knock-off Koyorad radiators selling their parts online. They make knock offs using the real company's logo and part numbers.

Koyoradracing.com (based in Japan) is the real producer.
Koyorad.com (based in Indonesia) is making fakes of the real Koyorad product. I have seen posts and videos online of folks who have seen them break down and start leaking, getting upset at Koyorad and not realizing that the product they bought is a fake.

For this reason I would not buy a Koyorad from any marketplace site (eBay, Amazon, etc), and would buy only from reputable suppliers. I found several on Amazon that looked real but were likely fakes (given slightly blurry logos, etc). I got mine from Evasive motorsports.

Funny enough, when the mechanic swapped in my new radiator, the old one he pulled out was a fake from Koyorad.com. I guess the previous owner was duped.

 

Good to know there are counterfeit Koyo's floating around. Almost bought one myself a few years ago. Glad it's working out for you dude.