dual exhuast questions

Ok I just got a set of headers for my 76 mustang II

Im planning on running duals with either flowmasters or the smaller canister type of mufflers.

What do I need in way of crossmembers?

What size of pipe will fit comfy? I have 3" left over from my merkur, but not sure if it will fit.

Has anybody try'ed the Xpipe kit from summit or jegs? I know we used it on a late model cobra recently and it sounds cool.

Any advice or help from anybody whos already done this would be great :)


Steve