Mart,

The relay coil is used in series with the trigger circuit.

Trigger wire ---> relay coil in series ---> resistor ---> base of transistor

A "choke" or any coil/inductor used like this builds a magnetic field when power goes through it. The magnetic field builds up and restricts current but still allows the voltage to get through. This is a very bare bones simplified understanding that might not do it justice but that is my basic understanding as I learned it from a different application.

I'm happy to see Sephiroth confirm with a tach that he did get higher RPM...just wondering what direction the turns of the relay coil are going in relation to the trigger wire.