johndavid,
First, welcome to the CAC.
When you say "performance", do you mean under racing conditions, or just driving around?
For just driving around, the car is perfectly happy to cruise along in 6th at 1500 rpms. You will get good gas mileage that way. However, if you want to be able to accelerate quickly, 6th is not really the gear to be in, and you will need the rpm's to be higher.
Just driving around town, I like to keep the rpm's around 2500-4000- and usually on the low side of that unless I'm interested in quicker acceleration. That's just me- others may have a different opinion.
I don't remember seeing any stats on gearing, rpm's and peak power.
Tammy