Y the problem with U/D pullies?
 

So I bought a set of U/D pullies in my car and installed them myself and notice a pretty noticeable difference. Besides me being a nublett and not putting RTV sealant on the harmonic balancer keyway slot it has done pretty well. I don't get why so many people have problems. All you need is an impact gun/harmonic puller/RTV sealant and the most BASIC of knowledge and you can install them problem free. I have never had a problem with them and have had them on for over 600 miles now. I don't see where these horror stories come from. BTW I tested it and ran my A/C, Radio @ full blast, and was @ 100 and the car ran just fine.

I think people just don't think it's worth the money. I've had them for both of my cars and did feel a difference with no problems. don't worry, when i install pulleys for my friends i put rtv on the key way and they ask me why i'm doing that.

most u/d pulley problems are from the 5.0 days. alt not charging. running hot and so on. the 4.6 does not have these problems