Removal of C6 does two things to my ears; it removes the top end fizz and makes the entire EQ more useable. The C6 cap is part of the high pass filter - this does exactly what the name implies; it passes only high frequencies. Removing the cap allows full frequency pass through and improves the sound of this pedal IMO. It is neither a bright nor a dark pedal. . .it is the only TS (ish) pedal that I have ever kept on my board long term.