The short answer is no, the dealer has no way of knowing your engine was tuned if you take it out before having your vehicle serviced. The search feature is your friend!
Here are many hours of reading for you to regard before making a decision!
+1 on the edge CTS2. It allows you to see any codes (I think. I have never had one:)) and also shows your soot % buildup and allows you to run a mobile regeneration at your convenien.It also has a couple other gauge options that are interesting to watch. If you don't want the suction cup mount...
I have seen a lot of threads about problems with the ecoD but I am not sure oil leaks are a major problem...That being said I would always be leary of a used vehicle that leaks oil.
There were only 2 or 3 counties in the whole state that had testing. (King and Pierce)I have lived here since the 70’s and have never had to pass an emissions test. It isn’t coming back.