I kind of doubt that it is the header, altho it might have helped it get that way, go get your hangers redone, i think that will solve your problem

 

It has nothing to do with the hanger, I had the Tanabe catback before my Invidia and it too was the same way, one side extremely higher than the other. It seem to me that somehow something got twisted from the header all the way to the exhaust, it's not the exhaust for sure and it's not the cat cuz I'd just replaced it with the T1R test pipe, same issue when the oem cat was still on so it's not both the T1R and catback system. Reason why I'd said it was the header was cuz when the oem header were still on that the whole system was hanging perfectly like how it would be, that's why I'm asking if anyone else had had the same issue as what I'm having. Take this as a heads up or need to know topic about the DC header, all I know is that at least my exhaust is hanging normally with the way I'd got it. Oem rubber hanger on the passenger side and a aftermarket (longer) hanger on the driver side so it holds the canister on that side from tilting upward, they're both hanging even as we speak.