I want to get underdrive pulleys for my 5.0 mustang

Question

What belt sizes will i need. They will have to be bigger than the stock belts correct? How hard are they to change for a beginner?

Answer 1

I found that they really don't give much horsepower.Your headlights will probably dim when you idle.

Answer 2

It depends on the kit, I have installed pulley kits from Kaufman products before and they still retain the stock belt.  The crank pulley is smaller, the alternator and water pump were larger to make up the difference.  As for installation, it is really easy.  If you happen to get a kit that uses a different belt than stock I would think the instructions would tell you what length belt you need.