So I am replacing the driver's side cat on my 1990 with a "direct fit" from Rockauto.com. It appears to be an Eastern Cat. Anyways after removing the old cat I noticed that the pipe and flange on the down pipe from the engine are not flush. The pipe extends maybe 1/4 inch past the flange. This is also true of the pipe leaving the cat that goes on to the Y and muffler. The old cat left room for this extension by insetting the pipe from the flange on the cat, but the new cat does not. Should I cut the pipe down to be flush with the flange and then mate it up with cat or is the new cat I have not correct? It looks correct in every other aspect except this.