Well i should point out that my mufflers were also custom so that very well could've had something to do with it. If say, you got Mac tail pipes and had a similar style muffler as Mac sells, they more than likely would fit ok. My flow tubes were custom and the mufflers themselves were 2 chambers cut in half, so i guess i shouldn't blame the tail pipes since i don't know if it was my mufflers causing the problems.
If they're a GOOD price, i'd try them out. You can always sell them to someone else.