Depends... ABS or non-ABS?
On my non-ABS '01 ST1100, I was able to use a 3.5" Rox Riser without extending the brake/clutch lines. I did have to reroute the throttle cable though.
On my ABSII '01 ST1100, I wasn't able to use the same 3.5" risers... the brake line that goes down to the modulator was too short. I was able to do the flip-clip mod though, which added about 1".