3 Piece Pulley Set - worth it?

Sounds like you are talking about a lightend pulley set, not an underdrive pulley set. yes you can see hp gains, I had underdrive pulleys on my mustang.
Lightened pulleyw work like this. The less effort the crank has to make to turn the engine over, the more hp you will make. Thus by reducing drag on the serpentine belt and making it easier to spin the belt and crank pulley you can gain hp. You mostly see the hp gains in N/A cars because the motor is doing all the work in making hp. You won't see many gains in turbo cars except for a quicker spool. Not saying you shouldn't get the. I am putting on a lightened crank pulley on my car.

Here is the link on eBay.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7982431767&sspagename=ADME:B:AAQ:US:1

in the pic the give, the left one is the crank pulley, the center one is the water pump and the small one is the alternator pulley. I wouldn't mess with the alternator pulley, I like have electricity flowing through my car ensuring I have a good spark. When I put my underdrives on the mustang the alternator wouldn't put out enough juice

lol i had a 95 5.0 to. I bought ud pulleys for it but didnt install them. Now that cars for sale. lol

but any aftermarket pulley, being lighter, or smaller, or bigger will cause a preformace gain weathers its big enough to tell idk, but it will put less stress on the motor.