Like most people I hava always heard the saying, stay with one paint co. products all the way thru, for obvious reasons. But I admit after 40 odd years doing my own cars. just mine as I am NO pro!!!! and you old not pay me to do someones car. I have used epoxy primers, urethane primers, poly primers, from SPI. PPG, DuPont, TCP Global, Evercoat and then topoats from TCP Global, PPG, DuPont all mixed and whatever. I 99% of the time topcoat with single stage and only time I cleared it came from SPI over a PPG single stage/ I guess I like adventure!? Go figure??