I had a good time with my new 20.00 high speed cutting saw last night. The holes had to be enlarged quite a bit. Initially I thought i would be able to make the cutouts similiar to how the kirkhams cut them, but the hole had already been cut too far back at the top, so i just ended up making sort of an oval shape.
It took 4 hours to cut this hole out. I had to install a pipe, remove a pipe, make a cut, install the pipe again, make another cut, remove the pipe, etc and so on. Im pretty happy with how it turned out. I went very slowly to make sure that i did not cut a hole too large.
Initially, i thought i was just going to need to give it a light trim, but once I installed the number 1 header tube, it was obvious that a good bit of metal needed to be removed.