I just bought a 1999 Yukon and have heard that you can change the "chip" which controls much of the engine's performance. I know nothing about this.<br /><br />If you have done it please provide some info. What kind of changes can you make? - - The good, the bad, the ugly.<br /><br />The Yukon will be my wife's daily driver plus we will use it to pull our 6,000 lb 23' double axle CC in southern Florida.