what is the code that is being thrown? without that we cant point you in the right direction, it could be something completely unrelated to the exhaust work

 

po141 po135

 

it keeps saying high circuit heater bank

 

First off it is called the PCM not a pcu.

P0135 1/1 O2S Heater Failure
P0141 1/2 02 Sens Relay

The P0135 means the drivers side before the CAT is bad. Go get a DESNO sensor or NTK sensor. Bosch sucks! Also check connections.

P0141 is a bad relay in the PDC under the hood. Swap with one of the same number like the horn, if it goes away then replace the relay.