So you already had issues with the turbonetics turbo as well?
I had a 7268 journal bearing running the stock on3 drain. What i think happened was the drain wasnt big enough and backed up, blew the seals out and coked everything. The on3 drain worked with my old on3 ball bearing setup with the restrictor. The lack of restrictor definitely changed things.
The new turbo is 7575 ball bearing fitted with a -10an drain. Hopefully the increased drain size will prevent that problembnbin the future.
All you have to do is weld in the the 4 inch to 3 inch v band reducing flange I think they are like 20 bucks . Mine goes from 5 inch out of turbo to a 4 inch down pipe. As Pate mentioned make sure to clean your MAF out good. I hadn't realized my old on3 turbo was pushing oil and it caused me a bunch of problems trying to dial in start up tune.
I looked at the flange adapters, only problem is i am running a full exhaust, every junction down pipe back we just tig welded ball and sockets to to finally make this on3 kit fit perfectly.. and then i had engine to catbacks ceramic coated. So the flange adapter would have messed up the alignment of all of my work down stream. I tried setting everything up with a 1.5 flange adapter since i didnt want to have to strip the pipes, cut and weld a flange then recoat them. Also i was under super time constraints, my wife gave birth to our daughter yesterday. So now my mustang time has disappeared. So lets hope this new one works well.
I wil definitely clean that maf before dropping it off at the tuner.