Strap-on boss into copper SVP

[Notapro]

Hello,
I need to fit a strap on boss onto an internal 108mm copper (yes, really) soil stack.

What is the best tool/technique for cutting out a 57mm hole? I wouldn't be asking if it were made of plastic..

Many thanks,

 

[namsag]

Save you the hassle i will come and fit you a new plastic stack for nothing and as a favor i will dispose of you old stack for you

Hole saw or a tank cutter which was designed for cutting into cyliners

 

[Notapro]

Thanks for the offer, but I think this might be less disruptive.