Continental Grand Prix 4000 SR Tubular Tire

I've been using Grand Prix 4000 SR's for the last two years on my Zipp 202's and 303's and all flats from punctures which were usually from small glass and throngs could not be sealed using vittoria pit stop foam or tufo liguid latex following their instructions. Raising tire inflation above 80 psi would start leakage all over again making the wheels almost useless except on patchy dirt road conditions. I have never been able to get over two thousand miles on any one of the several Conti 4000sr tubulars I have gone though. Better tires are out there.