I know some on the forum have reported that they extended their cables for the oxygen sensors and had no problem afterwards. Not so for me. I had to play with relocating the sensor bung along the exhaust stream. I also had to play with the height of the sensor in the stream. I am not sure what the problem was, perhaps the chip that was running the car, perhaps the efficiency of the 100-cats I am using, or the design of the header I have on the car (ttp).
I think we rewired the sensor a second time (we used wire from older sensors). Finally after months of messing around with it, we ended up replacing two of the four sensors and reprogramming the computer to have a slightly higher threshold before the CEL was triggered. The whole process took months to resolve, but it looks like it is now fixed, I have put 5K on the car with no issues except it is runninig great. I am not trying to scare you out, just sharing one owners experience, have fun,
Ed