Hey,
If you want, you can tap into the wires on the back of your gauge cluster. You just pull the gauge cluster out, route the wires from the HKS back there and tap in using the wire taps they provide.
Here is what they are from a post by JDM Sam:
RPM - violet/white
speedo - green/red
e brake - blue/orange
There are three plugs on the back of the gauge cluster, you'll be using the the middle and the far right harness on the guage cluster cut away some the tape and ull find em.