hello, im not going to answer your question as such, but im fairley new to NSR's and from what i understand "With NSR's its not an issue" sorry that sounds horrid. But apparently the Honda exhaust is so good that even an after market system will get you maybe an extra 2hp at best, i wouldnt worry and just get a set you like the look of... if im wrong please correct me someone! sorry this dosent answer the technical part of your question on shape and length but for power i think im spot on....

stand back and get slapped RC46