Ok, have new wheels on and really love them. I think 20" is the perfect size for me, looks great and is a proportioned size for the car I think, very happy with the ride etc. I fitted 255/40/20 Pilot Super Sport tyres on T-Sportline turbine wheels (I'll take a pic tomorrow). There is slightly more ride noise and did feel a slight frequency vibration on some hwy road surfaces but after 20 mins I forgot what the 19" stock Michelin Primacy tyres felt like and was already used to them. Slightly stiffer over bumps and a grippier feeling, but I was being super picky looking for extra noise and any issues. The stock Primacy tyres are designed for comfort so are going to be better in that way, but the look of the T-Sportlines over stock slipstreams and the grippy feel far out weigh the softer ride for me. Not sure about efficiency, am sure it's lower but would be negligible though. One thing is I bought new TPM sensors and even after a reset and 80kms on the drive home they haven't registered with the car, hope that happens soon and there isn't an issue.