The old days with no close ratio gears. If you had help, a 9 car would have a higher top speed than a 1600. Getting there was tough, but that long downhill helped. No restrictor plate and long 4th gear with 33" tires meant lots of top end speed if you could get there.
Here is what we ended up getting, GPS top speeds on the same dry lake stretch.
1st lap first driver: Driver was 220 pounds and car had a full tank of gas, 64 MPH.
120 miles later, second driver: Driver was 175 pounds and the car was lighter minus what ever fuel was used, 72 MPH.
Several factors play into "top speed". Aerodynamics on off road cars is usually horrible. Why can a stock bug with 55 hp do 80-90, and a 9 car with 15-20 more hp struggle to do 65-70? On a customers 9 car we added a 3" cardboard wicker bill, 3" in front of his "A" pillar at 65 degrees and got 4mph... Also, it's very common for 9 cars to be "under geared" meaning like a 1-2 1600, too low a 4th will limit the possibility of a higher top speed. I've passed a few 1600s on a lake bed with my old 9...remember, "pinned" in 4th, is pinned in 4th. The final drive ratio will only allow a certain top speed based on the rpm...simple math....
I raced a 9 car at Caliente about 10 years ago for the first time. I either started first or second in class and the 1600's started right in front of us. This was the old course that ran through the 3 big water crossings and the first 75% was graded roads with a sand wash or 2 mixed in. I ended up passing 2 known 1600 racers on a graded road and was going at least 5 mph faster than they were. I also learned you couldn't mandandle the transaxle the same way as a 1600 and grenaded the R&P going out on the last lap leading. Regardless I had a great time at the bar that night giving them I failed spelling that they got passed by a 9 car like they were standing still.
On another note Clint Braun won the jump contest at Battle at Primm between the 16's, 9's and 5/16's in 2016 and 2017. In 2016 a few of the 1600 guys called bs and claimed since he was pitting with us and a member of our team was doing the measurements we gave him the furthest distance and he got the bonus $$$. In 2017 he put in a go pro and he didn't lift from the hot pits all the way to the dike jump and confirmed it was no bull crap. The landing looked a bit harsh but he went for it. I think he ended up going 95' and the best 1600 went 87'.