Hi DS , I have an Idea that I am going to use eventually and you might be interested, also! The early decade(01'-03' I believe) gsxr 1000 header stock header is almost the exact diameter as my period 550 kerker pipe. If you have the means to modify it,(titanium) its a beautiful 4-2-1 pipe. The spacing at the head is not far off. The pipes would have to be modified between the 1st and 2nd elbows. Not as much would be needed if you could remote the oil filter. Pull up a pic of the pipe on ebay and take a look. You would probably need to to make one. Try to get them from the same year as Ti is pretty picky to weld.
Where are you in FL, I'm in winter park and atleast have one you can look at.
Just an idea and hope it helps!!!!
HB