DC9 CREW AND TWR LCL CTLR HAD CONFUSION ABOUT THE HDG THE ACFT WAS TO FLY AFTER TKOF.

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INSTRUCTED TO TAXI INTO POS AND HOLD RWY 12R AND 'BE READY.' AFTER TAXIING INTO POS; ADVANCED THRUST LEVERS TO 1.2 EPR (DC9 HIGH IDLE) TO AID IN ANTICIPATED EXPEDITIOUS ACCELERATION. UPON HEARING 'ACR XXX CLRED FOR TKOF;' RAPIDLY ADVANCED THRUST TO TKOF POS. I BELIEVED THAT FO ACKNOWLEDGED HDG TO BE 250 DEGS. AFTER TKOF; CLBING THROUGH 400 FT; STARTED TURN; SWITCHED TO DEP CTL; FO QUESTIONED HDG WITH DEP AND WE WERE INSTRUCTED TO COME TO HDG 230 DEGS. AFTER ARR IN IAH; I WAS ASKED TO CALL STL TWR CHIEF. OUR DISCUSSION REVEALED THAT THE ASSIGNED DEP HDG WAS ACTUALLY 125 DEGS AND NO TFC WAS ON FINAL REQUIRING AN 'EXPEDITIOUS DEP.' THE TWR CHIEF EXPLAINED THE DEP/NOISE CONSIDERATIONS; WHILE OFFERING THAT NO CONFLICTS OCCURRED. (MATTER WOULD BE DROPPED.) OUR ENSUING DISCUSSION OFFERED THE FOLLOWING SUGGESTIONS/OBSERVATIONS. 1) TWR CHIEF OBSERVED 130 DEG HDG CHANGE SHOULD HAVE SEEMED EXCESSIVE -- MANY ARPTS (IAH; CLE) REQUIRE 180 DEG HDG CHANGE FOR DEP. I OFFERED THAT DEP HDG COULD BE PLACED ON PDC; RATHER THAN SAYING 'HDG ASSIGNED BY TWR' ON DEP PLATE. 2) I OBSERVED THAT EXPEDITIOUS DEP WAS REQUESTED AND THAT IT WAS IN FACT NOT NECESSARY -- THE INCREASED NOISE LEVEL WAS DISTRACTING TO THE PLTS. 3) THE TWR CHIEF SUGGESTED THAT CRM COULD HAVE ALSO HELPED THE HDG CONFUSION.