The Y-pipe does fit, I know it is amazing. Considering the fact that I had problems too. At first I thought the flex pipe flange was warped (becasue it would not seal and it sounded like i had no exhaust) so i got a hold of Nick and he sent me another, well it was doing the same thing it turned out the be that I had the wrong size gasket, I then got one from autozone and viola it was sealed and I had some trouble with the 02 sensor holes but i end up going back to the original Y-pipe that he had sent me and it works perfectally with the new gasket.
Well fear not duratec owners me a nick are working on a revised y-pipe. I am sending him my stock y-pipe so that he will have it to take meausurements. Hopefully it will work out and we wont have so much difference between pipes built of the same jig.