First tank: 10mpg, 92 octane
Second tank: 12mpg, 89 octane
Third tank: 16.5mpg, 89 octane
I just filled the fourth with 87 and it runs perfect 6* advanced

I increased the fuel pressure to richen out my car a bit. It's still lean up top, but it's got nice a operating stoich. The car was driven with several redlines in each tank, combined city and highway (about 50/50). By the way, no new computer tuning has been done since the original custom PROM I had done a month ago. I'm getting increased economy from steady tuning the fuel pressure and timing. I'm using the stock fuel pump and injectors (as well as the stock TBI). Brian tuned my PROM for 55# injectors on the Holley 670, which is also why it's lean up top.

I'd think 16mpg average for my car the way it is, is absolutely awesome. I mean, it can only get better with new injectors and fuel pump.

 

Tuning tuning tuning. You are another example of results with constant tuning. A high flow fuel pump and that 670 combined with more tuning will do wonders for your car.