[Amps] How to improve efficiency

[R.Measures]

>I have a HB 4-1000 amp, GG, 6 kv on the anode, tuned input, PI output.
>
>Output (and input) is awesome on 40m, but I cant get the same steam on
>80m.
>I realize that efficiency can be variable from band to band, but what
>can be done to improve single band (80m)performance ??

**  Make sure the 80m tank operating Q is sufficient for the 
Z-transformation ratio at hand.