How have you found day to day running with this exhaust?
How is the gas distribution, have they resolved the issue of the left-hand pipe actually sucking, not blowing?
I've had my TT7 for a few years now. The original was rusting badly. It had holes in the box but didn't leak and passed the MOT.
Initially, it was really quite raucous burbling away at tick over and with quite a few pops on the overrun. It soon calmed down and is fairly quiet when driven conservatively around town. It gets quite boisterous when I give the car some beans and makes a glorious noise at 6,000+rpm. It has the standard catalytic converter. The only issue I have with it in terms of noise is that it drones quite badly at a steady 70 on the motorway, especially if the hood is up (not often!).
As for the gas flow, when the car is started, steam only comes out of the right-hand pipe but air movement can be easily felt at both pipes. As Perry says, once it's up and running, I have no idea. I've never noticed which pipe the MOT man puts his probe in when testing emissions. It's never been an issue at MOT time. If you look at the routing of the pipes in pics 4 and 7, it's not really surprising that the exhaust gas prefers the right-hand pipe at low pressure/revs. I've never considered it to be an issue.