Just installed my new 173 ecu in my 87 is. Haven't gone for a drive yet but just starting it I can tell there is a difference. Starts up and now idles around 700ish w/ my cam it sounds like a race car, very lopey but steady idle. Before it would hold an idle around 12-1500 then fluctuate. So I am quite happy so far. Only downside is I can't use my conforti chip anymore (153 ecu). Should have researched before I bought it. Oh well