underdrive pulley whit stereo system

The underdrive pulley reduced load on your car by spinning your water pump and your alternator slower right? But then that must means the car cools less or the when you have a stereo system like me that it doesn't charge your battery like it used to?

Is it a wise modification?

Underdrive pulley kits usually affect the power steering and alternator only. By spinning the alternator slow it's gong to cause it to run hotter at lower RPMS. For the 1-2 HO gain you'll get it's not worth it.

Well that's what I tought, altough I don't have any power steering on my car....

But I was also thiniking that it would effect the cooling of the engine, since the water pump wouldn't run as fast has it's supposed to, meaning less cooling....