I just installed a set of March "Power and Amp" pullies on my 93 last weekend. They went on really easily and I've seen no appreciable decrease in charging, at least according to the factory gauge. There is a noticable increase in power judging by the seatofthepantsometer.
http://www.marchperf.com/pg29.html
http://www.marchperf.com/pg29.html
No one can tell you what's gonna happen on your car in your location the way you drive. You'll have to try them and see. There are so many variables -- a non-air conditioned stock 5-spd. Stang in rural Canada in October with a new Griffin aluminum radiator is whole different animal than a boosted intercooled, air conditioned, auto transmissioned, Stang in Houston in August in stop and go traffic.
The underdrives slow down all accessories - including the water pump, alternator and the fan (if you have mechanical fan). Consequently, some people have problems with battery charging at low speeds when they install u/d's. Some people have cooling problems when they install u/d's. The only way to know is to try.
There are some rules of thumb - anything which adds more heat to the system, or more electrical load is not your friend when it comes to underdrives. So, if you have air conditioning, automatic transmission, tranny or oil coolers installed in front of the radiator, performance mods, intercoolers in front of the radiator, big amp stereo equipment, electric cooling fans, high amp headlights, etc. - you're more likely to have problems with u/d's than if you don't have those things. Also, if your radiator is original - you're more likely to have problems because it's likely lost a significant amount of it's heat transfer capacity.
The underdrives slow down all accessories - including the water pump, alternator and the fan (if you have mechanical fan). Consequently, some people have problems with battery charging at low speeds when they install u/d's. Some people have cooling problems when they install u/d's. The only way to know is to try.
There are some rules of thumb - anything which adds more heat to the system, or more electrical load is not your friend when it comes to underdrives. So, if you have air conditioning, automatic transmission, tranny or oil coolers installed in front of the radiator, performance mods, intercoolers in front of the radiator, big amp stereo equipment, electric cooling fans, high amp headlights, etc. - you're more likely to have problems with u/d's than if you don't have those things. Also, if your radiator is original - you're more likely to have problems because it's likely lost a significant amount of it's heat transfer capacity.