(Help)Installed ebay headers, now need advice on exhaust system

Hello like the title says i just finished installing ebay headers on my 04 325i, next step is installing a catalytic converter and catback. The only option i have are these magnaflow ones http://ift.tt/1jCCoI4. If i installed these in my car will any catback system fit on the end? Or will i have to do some welding or something crazy???



Any advice and help is well appreciated! :