If the dealer is looking hard enough, they will find out but in my experience, none of the dealers I have used give a toss about a simple chip.
Best bet is to get a serial port tune from the likes of APR or Revo. Arguably, APR is the tidier option as you can switch between programs (i.e. chipped, stock, 85ron, 98ron) from the cruise control whereas Revo uses a plug in module.
All other chips require a new chip installed in the ECU box therefore are detectable if this is removed.
I'm waiting for Starperformance.co.uk to get the APR serial hardware in then my S4 will be chipped with cruise added also.