I tend to agree with xp0s3d, though I don't think the damage is as prolific as he makes it out to be. Slowing down the water pump may cause the engine to run a little hotter, but it will make little difference on the highway. I imagine that it's possible to offset the temp difference with an upgraded radiator, but I've never looked into it. Also, the SVT's alternator is capable of handling a lot of AV upgrades by itself, so if you don't have extra power draws on your car (neons, amps, LCD screens, etc) you wouldn't have to worry about the alternator pulley doing any damage at all. Do a search for the "big 3 wiring upgrade" and you'll be set. As for the crank pulley, well that's a big debate. Personally, I wouldn't replace the dampener (which is what is on the crank pulley stock) with a regular pulley, so just leave it alone.
For the price of new parts, I don't think UDPs are worth it. If you can get some used ones for cheap, I think it wouldn't hurt in the short term. Just make sure you keep up on your regular maintenance and the car will last a long time. But like xp0s3d said, if you really want to spend your money wisely for power gains, save up for forced induction.