Almost 2k miles and no codes yet. The high flow cat is about where the stock 2nd cat is. The first O2 is about where it is stock and the snd O2 is behind the cat on the other side of the flange (After the flange to the rest of the exhaust). I think if I were to get any codes, I would have had one by now. Also, $800 built and installed for a 3" SS mandrel bent turbo back exahust is a good price.
Oh yeah, you can dirve the car with no front O2. It goes into speed density mode and drives just like stock......outside of boost of course. I drove it home with no 1st cat because it was siezed in teh pipe and they had to break it to get it out. But the car drove perfectly fine, I could boost, but there was no power in boost. The ECU is a very smart piece of equipment. Now if the O2 was giving incorrect readings, then it would probably have bucked and carried on because the ECU would be trying to tune to the car based on the incorrect readings.