Wirewrestler

I have some questions about this exhaust. I have an OBX Maximizer cat back exhaust for a thirdgen 5.0/5.7 camaro/firebird. My first question is any one familiar with this system and what are your opinions? Second, I have an 86 Camaro Sport 2.8L that I bought for my sons first car (exhaust new in box came with it). Solid car with 35k original barn stored. I have read throughout the threads and most people say not to go over a 2.5" exhaust and this is 3". I know the flanges don't line up at the cat and it would have to be cut and welded. We eventually plan to change out the factory t pipe with a better flowing y pipe and most likely eliminate the cat. Do you think this will work and should I expect any performance issues? I would think back pressure with the cat still there for now should remain the same. Any suggestions on the manifold pipe would be great too. Thanks for any help! Loving this site!