I bought a tube notcher, but I found the hassle in setting it up (what with the weird angles etc. we need to do) was more trouble than it was worth, IMHO. I ended up using my angry grinder & ultra-thin 4 1/2" carbide discs. After using the notcher for a couple of tubes, I found I could do just as good a job (or better) with the grinder, in about half the time - and with the grinder, there are no mistakes...open it up a little, test fit, massage it a bit more, etc., and it's perfect. Every time.
If I'd had my lathe back when I was doing this stuff, I'd probably have figured out a way to use that. 'Course, with the lathe, it's so much fun to use that even if it took longer to notch tubes, it would be more entertaining! "To the man with a hammer, everything looks like a nail..."
_________________
Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.
http://zetec7.webs.com/