After a quick google I can't find reference to 6ft from the turbo, just reference to keeping the temps less than 500 degrees C. Mine work fine....
Ref:
http://www.innovatemotorsports.com/support/manual/LM2_Manual_1.3.pdf
2.2 Sensor Placement
Using a bung is the preferred method for mounting the O2 sensor for both catalytic and non-catalytic cars.
On CATALYTIC CONVERTER equipped vehicles:
Install the oxygen sensor’s bung upstream from the catalytic converter (a bung and plug is included in the LM-2 kit). The bung must be installed in the exhaust pipe at the side or on top, NOT on the bottom of the exhaust pipe. Any decent muffler or exhaust shop can do this for you. The wide-band oxygen sensor is then installed into the bung to take a reading. (Insert the plug into the bung when not in use). The ideal position is between 10:00 and 2:00 position.
On NON-CATALYTIC converter vehicles:
You have the option with non-catalytic cars to also use an exhaust clamp as described below. Use of a bung is the preferred method for mounting the 02 sensor for both catalytic and non-catalytic cars.
On TURBO CHARGED vehicles:
Install the bung downstream from the turbo but before the catalytic converter. The high exhaust pressure before the turbo interferes with the lambda measurement and the high exhaust temperatures encountered there can damage the sensor.
Alternatively you can also use the optional exhaust clamp (part number 3728) to sample exhaust gases at the end of the tail pipe.
Document # 31-0008 LM2_Manual_1.3.doc 12
Do NOT install the Bung below the 3 o'clock or 9 o'clock position. Condensation can form in the exhaust pipe and permanently damage the sensor.
6 o’clock is the absolute worst position to mount the sensor.
Wide band oxygen sensors, like the one shipped with the LM-2, are designed to work with unleaded gasoline.
Use with leaded gasoline will significantly reduce the lifespan of the sensor. The reduction is directly proportional to the metal content of the fuel and the tune of the engine. In most cases, a wide band sensor will provide accurate measurements somewhere between 50 hours and 500 hours with leaded fuel.
WHEN INSTALLED IN THE EXHAUST, THE OXYGEN SENSOR MUST BE CONNECTED AND OPERATING WITH THE LM-2 WHENEVER THE CAR IS RUNNING. AN UN-POWERED OXYGEN SENSOR WILL BE DAMAGED WHEN EXPOSED TO EXHAUST GAS IF NOT PROPERLY POWERED.
The maximum temperature of the sensor at the bung (the sensor hexagon) should not exceed 500 oC or 900 oF. If these temperatures are exceeded in your application you should either install a double length bung (one inch) or the Innovate Motorsports Heat-Sink Bung extender (HBX-1).
The double length bung is also recommended for situations where airflow is restricted.
It is NOT a good idea to do a sensor warm-up prior to starting the vehicle.
Depending on the climate and the sensor position in the exhaust, condensation can form in the exhaust pipes. This condensation could then be blown by the exhaust stream against the hot sensor when the car is started. The resulting heat shock can permanently damage the sensor.
