I have had standard - okay for fast road use.

Radtec - VERY good - 7°C cooler than standard on track.

Pro-Alloy - On car now - 12° cooler than standard on track (but it was bigger than the Radtec item, so not a like for like comparison).

You won't notice ANY difference in them on the road, only in sustained use in hot track conditions. This is because the thermostat can control the temps on the road, so they all "appear" to be the same.

It's only when you drive on track and the temperatures start to climb above 100° that the uprated radiators come into their own.

I don't think you will have any bother with any of the well known ones .

AH Fabs, Radtec, Pro-Alloy etc. Avoid the Pace ones, as they are notoriously unreliable and the corners fail.