no issues. a lot of people feel better leaving the stock alternator pulley on. ive had my car sit in traffic on a hot day with the a/c on and my temp needle didnt budge above normal temp. it reduces the parasitic draw of power to the wheels. the stock pulley system loses supposedly 10hp to the wheels, (compared to the steedas) the UDP's are supposed to get that 10 back.
stock hp is 260, stock dyno rating usually 221 give or take, so according to their advertising, you get a peak hp of 231 with them. i never tested them, but i have em. people say it feels like it gets a bit more power and response than stock.
also do the plenum and throttle body next if your looking for throttle response. save your money and dont bother with a cold air intake unless you want the look/sound.
2002 GT 5sp. 16x,xxx miles
Steeda Exhaust, C&L plenum, BBK Throttle Body, Steeda Underdrive, Steeda short throw, unknown stage clutch. Rear main leak. Compressor seal leak. Steeda lower control arms. good tires.