more mustang questions

are power pullies from bbk really worth it will it make a noticable hp gain also i have an oe water pump and an oe alternator will it run hot and drain my battery and if so will getting a 100amp alternator fix the charging problem and a higher flowing water pump fix the heat problem.

also with the pullies and a 100amp alternator will i be able to run an electic fan like a mark8 fan or something like that

and finally i have a mechanical oil pressure gauge and when the car is cold i am reading about 55 psi but when it warms up and i am sitting at a stop light it goes down to about 15psi but the motor still idles fine and doesnt shake or nock and when i hit the gas it goes back up to about 40psi is this normal thanks:bigthumbsup