Sur de Texas flows reach record high, shifting US, Mexico gas balance   Mexico deliveries from pipeline hit 750 MMcf/d Friday US supply displaces domestic gas, activates latent demand     Transmission volumes on the Sur de Texas-Tuxpan Pipeline climbed to a record high late last week as the cross-border route continues to move more South Texas gas supply into central Mexico.   Deliveries Friday from the new pipeline climbed to their highest yet at 750 MMcf