I have been told to use a white sealer before I shoot my solid bright red to make it brighter, anybody done this?

Zach, reguardless of the undercoat color used you must achieve full paint color coverage if you ever plan on making repairs in the future. Using an undercoat color that shows through and effects the brightness of the paint will make repairability problems in the future. If you're looking for a candy effect you might as well do a candy.

In my minimul experiance that's true. I just did a yellow car and painting a white sealer really helped the yellow pop. I had to do a repair and the white/yellow/candy/clear was no problem. You could clearly see on the inside door panels where I didnt have white under the yellow and the color was quite a bit subdued.

Lee