I have SilMoto carbon oval cans on my 4S - good quality at a sensible price & nice noise too.
You can't "chip" the 4S as there isn't a removeable eprom chip in the ECU.
You may well get away without alterations...when I put Micron cans on my 900ssie the ecu compensated quite well and needed no alteration.
There are 3 options open to you.
First you can get your fuel mixture adjusted...this can be done using the ducati software that your dealer will have.
Next option is to go for an add on such as the Power Commander or Techlusion TFI ( that's what I have on mine - only because it was free though :P )
Finally you can buy a race can ECU ( these come with some of the DP systems, hence the price..) from either Ducati or FIM in Oz.
Hope this helps
Andy
[Edited on 1-3-2005 by Rushjob]