^^ What he said about he LS water pump and its efficiency for high RPM's.
LS water pumps are actually more efficient than VTEC water pumps but what happens is in higher RPM's it is spinning too fast and causing air pockets. How Honda fixed this problem was to basically make the VTEC water pump less efficient.
I believe that VTEC water pumps have 22T and non VTEC water pumps have about 18T? But both have the same amount of blades on the inside pushing the coolant through the motor. The more teeths for the timing belt would make it less efficient but prevent the air pockets from producing and is therefore more productive cooling at higher RPMs hence the VTEC timing belt.
Also, with the extra few teeths the VTEC timing belt in your case (GSR / Type R) will be a little bigger. Technically you can use a LS water pump and LS timing belt because the amount of teeths line up as well as the Head and Block height (B16 head and block height is much shorter so you would not use same timing belt). BUT you wouldn't want to do that because if you're planning on hitting VTEC it wouldn't bold so well with cooling the motor.
So.... get a VTEC 22T water pump and a P72 timing belt. You should be good to go.
Also, as others has stated, check to make sure you installed everything back properly. It seems as if something is rubbing the timing belt.
Good luck!