Bought Flowtech Midlength headers, O2 harness wont reach the Header. Help?

[TBI355]

Got true 2 1/2" duals put on, the shop didnt put an o2 sensor bung in the pipe because the header has one, but the harness that comes out above the transmission will not reach the header. Should I plug the header bung and weld one in the pipe close to the harness? I've heard thats too far away with headers and the sensor wont get hot enough. Anyone have these issues?

 

[Tempted]

http://www.amazon.com/Setter-062253-Sensor-Harness-Extension/dp/B00133L1DS

 

[TBI355]

Thank you, I just bought it, hopefully it works. truck kind of loads up around 10% throttle.