Since I had it the truck has been running rich?

You should switch the bank 1 and two sensors and swap them, if the code goes with the o2 sensor then the sensor is bad, if not its engine related. Check to make sure the injectors are not leaking or the fuel pressure regulator is bad. Also check the MAF sensor.

I'm not too familiar with the BBK filter set-up. If it is anything like the K&N filters that require being treated with oil, then I would suspect the MAF sensor. The other thing you mentioned that I have seen before is the modified exhaust system. If you have modified cat converters or no cat converters at all, then the downstream O2 sensors are not sending the signal that the computer is expecting. This can cause a rich condition on the upstream O2 sensors. Find out what they have done to the exhaust and if there are even any downstream O2 sensors. I've even seen installers use a shunt and leave out the O2 all together. All this info will help us determine what's going on. Blackop555 is correct, though, check the obvious first and then consider the obscure.

Leaving the 02 sensors are a problem all too common when using after market exhaust. But id be checking the MAF sensor first, since aftermarket air intakes are known for this.