Thinking back, my terrible understeer happened for the initial 3 years of my ownership on the old shocks. I recently had the shocks replaced so perhaps that could be why it was understeering. I will try 45/41 again to see if it's actually better. I personally felt the lower pressures makes the car feel more planted, especially downhill with the weight of the car. But then again canyon driving is very different from tracks, there's hardly any straight that allow you to get to above 125mph (except perhaps Ojai hwy 33, with everyone doing 150 and above), so maybe the high pressures are more appropriate for track speeds. I will give 45/41 a try and then 39/36 to match the facelift cars.
One thing which I find rather odd, which perhaps have nothing to do with the topic, was that when i was doing 45/41, i almost have to re-inflat the tires everytime after 1-2 weeks. It seems to lose air if u do 45/41. When I adjusted them to 36/37, I almost dont have to inflat for a year as the pressure's always constant. Always wondered why this is the case