Gearbox issue was an external issue (cracked mount boss).
My car will only have 2 cats when I get it back!
The power delivery you describe is the same in my car with the exception that I feel little to no "mild increase" @ 4000 or "hike" at 4500rpm. It's pretty much flat across the rev range. I agree that little is gained by reving past 6500.
I will be purchasing a durametric soon to see what I can find on my own.
Thanks for the well wishes.
Cheers!