TC Spark booster not enough treble

[cooder]

I built the Ember boost TC Spark booster and find it lacks some treble and spunk even when I have the treble maxed out.
So you circuit hackers: any hints what values to change to increase the treble content and give it more bit? I guess changing the 8n2 cap 16 should make a difference but I'm a bit stumped which way to go.
Others here will have more insight there I'm sure... Cheers.

 

[mywmyw]

are you using low capacitance cables?

 

[cooder]

are you using low capacitance cables?

Inside the pedal it's Smallbear 24awg wire and on board low capacitance instrument cable. None of my other pedals (there's a bunch...) have a loss of treble and also similar pedals like Timmy clone are just fine. So I guess it's the values used or maybe I have a bad solder spot or mixed up component. Otherwise pedal works just fine. I'm just wondering about tweaking it.