okee i have a sollution.. i have the same mods
a catback and a cai.
the solution is simple..
If you lift the second sensor.. the 1 after the cat up bij 2 inc, the sensor is "smelling" less so the ecu is thingking that there is a cat onder the car.
I have a picture @ home.. i can put the picture online tonight.
this will solv the problem and you are happy