how much would you like to remove?

to try and maintain the masts bend characteristics, you could take a bit off the top and bottom

if you take too much from the bottom you risk not fitting the mast base/extension properly, and too much from top might stiffen the feel of some masts

I have cut down a couple of older sdm np masts and they seem to work ok, both are old c30 s one went from 460 to 430 with all cut from bottom, I use this on on a np 4.5 wave sail (older sail not sure what year but it has on it 10 year anniversary dunkerbeck limited edition) the other I cut about 10 cm off the bottom because it was split and have been using this on an aerotech 5.8 wave sail circa 2006, only problem its a bit stiff on bottom as bottom batten doesn't always rotate properly have to give it a gentle kick sometimes when coming out of a jybe.