long story here...
my first car was a '79 Grand LeMans when i was 14 in 1991. Nice enough car, factory buckets, and console. 350 chevy from a '73 monte carlo( according to the numbers)
being i had a few years before i could drive it, and being young and dumb, not fully understanding drivetrain " combinations' , i decided to start modifying. i did a comp cams " 268 high energy" cam, dual plane intake/650 holley, and cheap headers, and a custom dual exhaust that my dad paid for as a gift. ( the car was flatbeded to the muffler shop for this, as i still has a few months before i got my license.)
now comes the first drive... should move pretty good with the things i did right? NO.
the thing was a stone. i remember getting passed by a full size dodge conversion van, who looking back now, probably didn't even know i was floored... and it got horrible mileage. BUT it did loaf along at something like 2,000 rpm at 70...
after 1 to many 1 wheel burnouts, the rear exploded. THAT'S when i started to understand it's not just about the engine.... pulling the cover and counting ( what was left) of the teeth, i had to count multiple times to believe what i was seeing.. a 2.29 final drive ratio. being a broke kid going to high school working something like 20 hours a week, for minimum wage, i borrowed money from my father to buy a complete rear from a monte carlo SS. that had 3.73's.
Holy Moly! did it wake that car up! it would burn the tires going into 2nd gear. not only did the performance improve, so did the mileage! i could not go almost 2 weeks before fill up, where as before, it was at least once a week! but hey, premium was only about $1 then!