An Underdrive Pulley Add On

[GasSavers_goldie]

My vehicle is an 07 GMC Sierra with the 4.3L engine and a 5 spd. manual, the truck has 16,700 miles on it. About 10,000 miles ago I added crank and alternator underdrive pulleys. Contemporary advice at the time suggested strongly that my vehicle would run too hot with the water pump underdrive pulley. Subsequently, I have been told that the radiator in my truck is the same size as used for V8 engines. If this is the case, overheating would not pose a problem because of the extra capapcity even with a slower turning water pump. I would like to add a water pump underedrive pulley to increase my power (i.e. economy). I'd apprecaite any suggestion and especially real time experiences. Thanks in advance!