it goes in parallel with the 2u2 ... I suggest looking at an rc filter calculator to see what it does that section of the 2nd order filterI think i try the 6.8 uF with the original 4.7uF in parallel, if not enough i go with the lower side of the G Tranter mod (560 Ohm and 4.7 uF in parallel).
You are right. Its the higher RC network that should come down from 1526 Hz to about 376 Hz.it goes in parallel with the 2u2 ... I suggest looking at an rc filter calculator to see what it does that section of the 2nd order filter