I think this is why they split into 3 different product lines. It used to be that "Professional" was the same thing that came on your car (although enough decades ago, every AC and Delco and Remy, etc. part were the originals), but they've slowly phased that out. Now they also offer the "original equipment" line, or whatever it's called and Professional falls between that and the "Advantage" (competes with store brand parts). I think we all feel the quality has gone downhill, but in some cases AC Delco professional is the best part available.