I'm really not worried about dealer scrutiny regarding a downpipe or FMIC. As I said, my dealer is pretty mod-friendly and none of those components are likely to fail and/or be the cause for anything else to go wrong. I mean, nobody's intercooler just breaks. What I want to avoid is that worse case scenario of engine failure or turbo failure and the dealer's computers detect a tune and the info is logged for BMWNA to see. My dealer claims that even a piggyback will store shadow codes that corporate can see if they have cause to look.
Dunno if that is true or not but I don't plan on finding out.
I am primarily looking for a lag-free experience and ultimate drivability, not building a show car for making street racing videos on the intenetz.