I am of the opinion that any flash is detectable.

Be it locally, if the dealer suspects... I believe BMW has fields that track programming events (not just the 'tune', but how many times the code has been changed. etc)

Or if a rod leaves the block and BMW asks for the DME to be sent in for forensics.

I prefer recoding the DME/DDE as I believe it is a superior approach and will give safer and better performance. But you need to let go of the warranty, ultimately,m and recognize you may pay the piper