If you want another alternative, people on the board have been happy (including myself) with the Hankook Ventus K104s. Excellent for the price, and if you do a search, they do hold their own against the competition in the last MOTOR mag tyre shootout. From the figures, the K104 does do a admirable good job. The FK451 did even better. Sorry but I dont have any info on the sumitomo besides this survey in EVO Magazine (best to worst);
1) Goodyear Eagle F1 GSD3
2) Toyo Proxes T1-S
3) ContiSportContact2
4) Michelin Pilot Sport
5) Dunlop SP Sport 9000
6) Pirelli PZero Nero
7) Bridgestone S-03
8) Hankook Ventus Sport K104
9) Yokohama AVS ES100
10) BF Goodrich g-Force TA KWD
11) Firestone Firehawk SZ50 EP
12) Kumho ECST Supra 712
13) Sumitomo HTRZ II