I hate to make another "unresponsive" response to your question about the location of the high beam relay, but I don't know. Something to think about if you haven't made your purchasing decision yet:
I installed a Wolo air horn and the Signal Dynamics headlight modulator and they work together to flash the high beam without needing to know anything about the high-beam wiring and its relay. The Signal Dynamics modulator has an input for the horn voltage and automatically flashes your headlights brighter when you sound your horn. A double-tap on the horn also changes the headlight modulation from medium to maximum, both of which are DOT approved flashing levels. I liked that all the signals for the horn/headlight integration were easily found near the headlight and I didn't have to cut into my harness.
http://www.signaldynamics.com/headlight-module/