I generally believe in following the manual, which has an absolute prohibition, but the way I see it is there's nuthin' wrong with cuttin', drillin', weldin', etc. as long as you know and understand that you ain't gonn sue the manufacturer and win if you turn it over and the ROPS collapses, you may (or may not) have to replace the ROPS if or when you trade it in or sell it, and there's the possibility of being liable yourself if you sell it and the new owner turns it over and gets hurt because of a modified ROPS.
Now I figure there's only a slight possibility of any of those bad things happening, but there's still the possibility, so I would never recommend to anyone else that they do those things . . . but, I also once drilled four quarter inch holes in one of my tractor's ROPS. /forums/images/graemlins/crazy.gif /forums/images/graemlins/laugh.gif