Hi, currently I've got 3" cat back kakimoto regu 96 exhaust connected to the cat, but I have 3" decat waiting to be fitted and now the problem is that standard cat is 2,5" so I need to change centre section for 3" one so I'm wonderig if it worth to just change centre section and use regu back box or is it better to get different 3" decent cat back and swap it all? Thanks