I ran out of epoxy so I called Barry at SPI to order more, he told me it's not necessary to use a sealer. He said to sand with 400 then paint which I was happy to hear because I saved $200 and it would add so much more work for me to use a sealer. As for using what I used, PPG Deltron 2000 DBC BC/CC over SPI epoxy and universal clear over the PPG paint, he guaranteed me there would be no issues. So far he's right.
Here's where I bought my paint.... http://www.ebay.com/itm/PPG-Deltron-...285394&vxp=mtr