Ok im spraying my chevelle in a metallic so im going to go with a 600 grit final sand to finish of my primer. But im going to use Chroma Premier sealer and then spray my color. I was just wondering from the expert opinion should i go wet on wet or let my sealer flash OR let it dry wetsand it down with the 600 grit and then spray my base.

The Chroma Premiere sealer is some excellent stuff IMO, it sprays nice and thin and covers well. There should be no reason to sand the sealer before basecoat application other than nib removal if there's any specs. Shoot a nice thin coat on and let it flash off well, shoot your base with plenty of flash times between coats then allow the last coat of base to set 1 to 24hrs. and you're ready for clear. What color are you shooting? The only exception to sanding before basecoat would be if you're shooting a very very fine grained metalic or pearl like some silvers- they need an absolutely perfectly smooth surface with no traces of any texture at all.