Outboards 20" or 25"

[bksah2]

I got to say,, latelly I have seen so pretty good deals on used outboards on Cragslist/ebay ,,,But they all seem to be 20" shafts and not many 25" shafts ..On my v20 i have a 25" and was wondering if i wanted to go to a 20" do i really have to cut down my trasom the 5" or can i just bolt on a 20" ,,,would there really be that much of a performance differences /handleing differnces