another option for dent removal is to take the pipes off, put some water in the dented one, and put it in a freezer overnight. The water expands and pushes the dent out.
Yeah,I've heard of this trick before for gettin dents of of metal gas tanks, but I've never tried it. Have you? Just my opinion but it seems a little risky to me, The ends would have to be capped to hold the water/pressure in and If freezing water can crack an engine block I'm not sure I'd wanna see what it'd do to my pipe.
Again I've never tried it so I'm not speaking from experience. Anyone who has actually done this feel free to chime in and tell me how wrong i am, I'm all about better/easier ways of doing things.