Oh I see now..The way the one side was bent it looked like the pipes were 3.5". So You are going dual 3" to single 3" to 4" right? Why not just skip the 2-into-1 3" Could you not find the adapter?
You would not believe how hard it is to get Y Pipes etc. The only ones I found were the same size through out the whole Y. I would need to build my own to do that. The 3" to 4" 90* reducing bend will take care of the whole thing and it will be nice and clean too..
There is a big thought process that goes on with a build like this, you change one thing and it affects the next. You are forced to think 2 or three steps ahead which is a BRAIN STRETCHER at least for me anyway!:dontknow: