I assume heat on the intake and cool the pipe with an ice cube or something before attempting.

Shouldn't there be a socket like tool that fits those groves or something? If I reccall the last time I did this I was lucky enough to have some angle iron that fit the groves and strong enough to twist on. I don't scraps of metal like that where I'm at now but it might be worth my time to go find some as it comes in handy from time to time.

Do you think filing the groves open wide to accept a wrench handle or something with a bit more meat will be bad for it? Seems to seal on the flat of the pipe where the clamp will be and not the end anyways?