2-pc EM question

[Ken Keith]

OK, I've got a simple question.

Should I, or shouldn't I, taper the walls inside the collector at the turbo,
on my 2-pc exhaust manifold.

Here's a pic put up by Gerard (thanks G.!)

http://www.2226.co.za/manifolds/turbo-weld-003.jpg

My concerns with doing this would be that it might weaken it and cause
it to crack due to thermal cycling.

Another possible concern is that it may serve as some sort of an anti-
reversion lip, and tapering it might be counter-productive.

With all this talk of 2-pc EM's cracking, I believe I will be investing in
some preventative treatments to the EM, like cryo treatment and
ceramic coating.  If so, I want to do any modifying beforehand of course.

I think there was a pic up at one time of the EM with those inner walls
tapered/sharpened (knife-edged?).  It may have been Jeff G.'s old site.

Thanks,

Ken