2004 gmc denali remote start

that has to do with the alarm system communication(a plug that connects directly from the alarm to the bypass module).  I would go with DEI systems which are more installer friendly and sadly enough are widely availabe online.  I've heard good things about compustar but my favorite for sure is the viper 5900 which is a 2 way model and is 1 mile range.  Another note, compustars(i think) have that port for the 1 way or 2 way and you wouldn't have to match the wires anymore, the data is already going through one of the plugs but then again you have to get your hands on one and find out which port works with it.  Good Luck