No. You re-route 5 peak HP (if you get that much) to the wheels for $200. The motor still makes the same HP it did before the pulleys.
It doesn't care what you do with that 5 HP until you start affecting charging and cooling. The power steering pump may complain during low speed driving.
The only pulley that I've seen "make" HP is the one on my blower and even that is debatable.
I put underdrives on my car a few years ago. They look a lot better than the stockers and I've never experienced any charging, cooling or steering issues.