RR4 is a nice system that gives lots of data from the <em>IS</em> engine sensors. It does not give you the most important sensor reading, EGT. It is Insite in a box.
All in all, my preference is for gauges.
I have an electronic version of RR4 user's manual in MS Word. PM (with your EMAIL address) if you want a copy.
diesel on
-John
edit
I need an email address if you want a copy