Originally Posted by semtex

I'm not sure I'd call piggyback units a 'hack job'. I think it just depends on the quality of the unit. I do prefer ECU reflashes though. They just seem 'cleaner' to me, if that makes any sense. But ECU tuning is definitely not my area of expertise. In fact, looking at the AFR data, I noticed that the line slopes downward as rpm increases. Does that mean it's getting leaner as rpm climbs? Or richer?