I am wondering what would need to be done to take my gil risers and make them a dry to the tip pipe. Can this be done without to much complicated effort?

Can't say that it's not complicated without seeing what your working with now. I'm assuming that you have exhaust hose from your risers to your tips now? If so you'll need to have someone fab you up some double walled tail pipes and a way to connect them up to your risers. It's not hard for someone that knows what their doing and it's not cheap but then again, what is?

That is correct, My risers are about 3 inches from my transom and I would need them to be extended by a foot or so, gotta be cheaper than buying new????

If their that close and are a straight shot back thru the transom then any fab shop worth their salt should be able to extend your risers to the needed length.