Remove the resistor and just leave the capacitor on it's own between the centre and outside tag of your volume pot(s) - that's how I do mine.
Adding the capacitor alone will retain the highs as desired, but the resistor could/will be adding a value in parallel with the track of your volume pots, depending on how it is wired.
On my Telecaster I always do the capacitor only mod and it does the job perfectly.
:D
