Alternator and pulley question

Hi all,

What is the smallest size serpentine alternator pulley that I can use (have made)?

I am looking at KRC's pulley system ( for my street car) but their water pump and crank pulleys are only 4 inch.

This will be a street machine with EFI, electric fuel pump, stereo, locking, alarm etc and I am also not sure what amp alternator would be best to use.

HELP HELP HELP
Author: admin