Agree they are noisy but it's always a compromise for the level of grip. To be honest will not put them on the fronts again that's were most of the noise is coming from.
Have sound insulated the entire boot to rear seats which made a huge difference.
The revised version (R888R) are a little hard to get atm, more availability in months to come. Review states improved mid-corner grip.
http://toyotires.com.au/tyres/motorsport-tyres/item/1250-proxes-r888r
Agree the larger the tyres footprint the better, the next size up will not work, will foal on the inner guards when she squats under load.