I did this on my gt tdi and it was fine, doesn't change anything apart from looks.
Yes it's fine.You'll need to mate the backbox with your centre pipe somehow as they are different diameter, I bought a clamp on eBay for about £8 which was for a 55mm to ~63.5mm sleeve (it needs to be a tad bigger than this to slip over).Cut the exhaust myself with a grinder, you could get an exhaust place to fit it for not a lot of money.The hanging points are the same