IMO and no offence intended but they are a poor design in the collector,
and i personally never use thin wall exhaust tube for turbo manifolds, let alone pressed collectors.
i always use schedule 40 tube and bends, a lot heavier but a lot stronger, retain more heat and generally will never crack. and dont need as much bracing to hold the weight off the turbo.
When i fabricate manifolds i cut and scallop each pipe in such a way that all 4 can be directly welded to the turbo flange and merge evenly. welding them can be tricky but with a bit of patience its not generally a problem
ill try and dig out a couple of pics.