Looking for wah output buffers

[warioblast]

Hi,
I built a wah months ago and added an ouput buffer (from fuzzcentral). Though there's a huge improvement on the tone of the wah, I realized it denaturated too much the sound of my fuzzfaces, adding an unwanted octave-up sound. [ In writing this thread I suddenly realize I didn't make transistors swaps in the wah; right now it's loaded with BC109B; may be... ]
Has anyone ever expericend this ?
What other output  buffers can I try in my wah ?
Cheers,
Fabrice