I checked all the lines that go to the bcs, intercooler and throttle body hoses, and all the bolts on the uppipe and downpipe, is there any where else that could be leaking boost? could going stage 2 just have put too much stress on the old bcs?
First it is not the rear o2 which you don't really need. Nor the front o2 for that matter - that one is important for other reasons though.
Second it can't be your BCS unless it is stuck open. When they fail they usually don't open, which reduces boost. Even if it were stuck open I don't think you'd get runaway boost at all.
Are you getting runaway boost (you hit 22 and saw it and let off) or did it just peak at 22? If you did you have a leak in a BCS vacuum line, no restrictor pill, or your wastegate actuator should be checked. Is it springy and pretty damn hard to pull open?
If not, load the LWG map and do the log. Your car will pull timing to protect itself if needed. Be sure you read up and get the parameters for boost control without too much other stuff other than the standard knock control, IAM, RPM, TP, load stuff.