I've read they don't do much for our vehicles... and just to give your manifold a clean as well as walnut blasting the intake ports on your heads. Something to do with heat causing oil vapors... bypassing the catch can for the most part. But don't quote me on that.
Light Bolt-ons, Tunes, & Methanol Injection:
12.30 @ 115mph [2.0 60ft on Street Tires] [91 Octane]
1.59 Seconds Faster than Stock [as of 05/29/2014