check my other thread its more put together.... i did this last night at 2 in the morning on my black berry and it looked all scrambled and like crap

 

That sounds like a tall idea. Just a few ?'s
Type of bike? That would help. Just beacuse you posted up here doesnt mean that its an f4i. What year is it?

As for type of metal i would stick with the aluminum just because it cools faster and is not as heavy as the stainless.
Is your idea something like the 600RR design?

 

would it be possible to get an aftermarket 600rr exhaust and modify it to fit your bike? your price range would be shot, but it would probably be easier