20 years ago my 4000+lb. streetcar/show car Chevelle with the stock 396/350HP under the hood was running mid 12's with a Q-Jet and through a full exhaust system.
16 years later and the year it was sold, the same all steel show quality car, now tipping the scales at 3880 lbs., still with power steering, power brakes, tilt wheel, full factory interior and a full exhaust under it ran well in the 9's with a restrictor plated 522 under the hood as well 137 MPH, wasn't backed by a $6,000 trans nor run in -500 feet air either
and the pump gas, cast iron oval port headed 468 that was under the from '95 to 2007 ran a best 1.28 60 foot and 10.07 @ 131, 5 years ago in 2007 as well it was quicker and faster than every 468, 496, 502, most 540s and GM's 720HP 572 in similar weight, small tire Chevelles competing in Division 1 brackets.