I had the same issue. Scraped up left stock can when I bought SP1. I got a smoking deal on some clean stock cans off a sp2. Neither side would fit on my bike. I had to cut the pipes and reweld them to make it the right shape. I only did the left side. I didnt actually weld it, but i did do the other stuff. My welder told me it was real tough to weld cause he just couldn't get the inside clean enough. If you go fullscreen on the picture, you can see the porousity. I know it looks rough in the picture, but that's about 4 inches away from it.
Oh yea, it's ok to laugh at my footpeg. That's temporary till the harris pegs get here.