It says to mount the bung for the sensor at least 18" from the exhaust port.

That would put it in the middle of the exchanger

Can I mount this in the pipe after the exchanger and before the muffler or is that too far away from the head.

How have you done this?

Thanks
John

I had a bursch muffler and mounted my sensor in the collector after the heat exchangers. It worked great for me. Just make sure it is mounted between 9-3 on the pipe to prevent moisture buildup on the sensor.
My sensor is also self heating so that may be a factor in how close you need to mount it to the port.

Hope this helps.

I am using a stock muffler. It will be easier mounting there tnan on the harder stainless pipe.