I believe that power enrichment is used to protect the cats so that they do not overtemp.
If you install an O/R H or X Pipe, you have opportunity to lean it out a bit. However, a good rule of thumb to keep everything cool (exhaust valves, exhaust manifolds, etc) is to keep the A/F around the 12.5:1 range.
P.S. I am pretty sure that dynamometer engine durability testing usually keeps the A/F around 12.5:1.
The chip will correct the A/F ratio. 12.9 to 13.0 is a good number to shoot for for max power. I installed an A/F gauge in my 85 LX. This was one from Nordskog,a high quality full sweep analog gauge. It is fairly accurate,and by trimming,leaning my carb jets a little,produced the best MPH to date in the 1/4 at that A/F ratio.
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