how much would it cost to have turbo sized flanges converted to NA?
 

I am wondering because I would like to get a presilencer that is made for turbos but I was told would work on NA's just fine, the only problem being the ID of the flanges. This is the presilencer http://www.racingbeat.com/RX7-1986-1...ms/16425P.html
Does anyone have any experience of having their flanges replaces or modified to a smaller size? 2.4 ID in this case. I am assuming the ID on the presilencer is 3 inches (80mm/3.1)

just get a Borla XR1 and weld it in, no messing with swapping flanges or any of that.