The Scanmaster is a very useful tool. It not only monitors your knock retard and 02 millivolts (which are both very critical on these cars) but it can also tell you the speedo mph, coolant temp, air intake temp...if the SES light comes on it also displays codes....very useful tool to have.
If you don't already have the Turbo Tweak chip I recommend you splurge $85 and get one. It will allow you to change timing and fuel curves via the Scanmaster. Plus it will run better as the TT chips are made to run on todays gasoline. Your ECM might even already have one. Pull your right kick panel. Pull the small cover off the ECM, I think it's a 10 mm screw. It will say Turbo Tweak on the chip if it is.
And yes the GN is not like your typical small block Chevy or Olds. For the most part the GN has all sorts of gizmos and such that require a new understanding. I've sort of summed it up as the ECM times the ignition and injectors and relies on the MAF, TPS, Cam and crank sensor and some other things to make it all work.