it can be easily fixed, I just need to ensure the mounting face is concentric (hammer time) and then install it gently (after bolting it to the cat back section first, so it doesnt bend that face).
its not bent, just the boltup flange isnt sitting flush, it can slide up and down ... just takes some jigging about really.
currently spending a month at tafe block training, and at thornlie tafe the driveway has about 10 speed bumps to the carpark.... once not at tafe, I dont encounter a speed bump on my way to work