I personally think the pcm still adds to much timing under the Bad Fuel SPark table. If I recall correctly, the pcm (97-03) adds around 8 degrees of timing under full load on the BFST. Under the 04+ grand prixs, the pcm pulls the timing to like 0 under full load under BFST. I uploaded an 05 comp g timing tables to my gtp and the cruise timing was increased from around 30 to 44 degrees of timing. While running on low octane fuel it drops the timing way more than my 97 bad spark table. The 04+ gtp's say you can run on regular fuel but your power will be reduced and that would be partially because the timing was pulled

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1997 Black GTP 72k (4dr), 3.5 Pulley, Wbody Downpipe, Wbody Shift kit (street), DHP 1.0, NGK TR55ix Spark Plugs, GMP Handling kit, KYB AGX Struts, AT Italia Inox 235x50x18 Bfgoodrich KDWS, GMPP Springs, Corvette C5 Calipers, Blazertech 3200, DHP Powertuner (97-03), Built Trans, Torsen Diff