I have done a search and read through them but all I have found is members saying that they have them and are going to install and not a followup.

I have a set of underdrive pulleys sitting on my back seat. I am on the fence on taking them back and using the money for either stereo/speaker upgrade or some nerf bars. I have a 08 crew cab with the 5.3ltr. I have a custom tune, dynatech long tube headers & cats, corsa touring cat-back exhaust, and a cai. To those that have installed them in a 07-up nnbs was it worth the install?
Thanks,
Larry