Walker HDL in bi-wiring set up. Woofer or tweeter?

Proac Reference 8 Signatures bi-wired powered by Cary CAD 300 SE, through Speltz's zero boxes set at 1.4X (impedance at around 11 ohm nominal). IF I want to insert Walker's HDL, should I do it at the tweeter or mid-woofer? I know I should use 2 sets for bi-wired speakers, but just want to try 1 set first. Thanks in advance.
The biggest effect of the HDLs is to eliminate hash in the upper frequencies, so it would make most sense to put them on the tweeter in a bi-wired setup.
I had a tri-wire setup with the HDLs. While they do affect all frequencies, I found the most noticeable (and measurable) improvement was in the high frequencies, so I agree with Rush, I would start with the tweeter.
Thank you very much for your fast replies, Rushton and Rcprince. Will try it out this weekend.