Hands down the best setup is the CTS-V Alternator and bracket with Shane's belt tensioner. Especially if you are going with a bit higher HP.

Make sure you get the right alternator as Cadillac changed over mid year and the old one needs a PWM signal to turn on and that's the one I got as I can control the output voltage with my ECU. There are a few large threads on the other forum with details you can read up on.