Mph is not bad ,but, et is about what most bone stock F bodies run. I have an 01 Z28 with 165,000 A4/3.23 gears. It ran 8.7 @82/ firstname.lastname@example.org ,2.14 60ft with a bad headwind in +2500 DA. It ran 8.63@83/ email@example.com in +900DA and no headwind. firstname.lastname@example.org / email@example.com ,2.04 60ft w/ ported t/b and spare tire/jack, back seats removed in +850DA. What was the DA at the track when you ran? Make sure your plugs look good and fuel filter and air filter are good to go. With a 2.0 60 ft you could run 13.30-13.40 in same conditions which is not bad for the mileage.