Replacing the front fork springs is the best way, and I did change Bel Ray 7.5W fork oil to stiffen the dampening a bit as well. This video is from the Self Help section, Fork Lowering, but it shows how it is done Progressive' lowering kitm which uses a spring instead of a solid spacer...! That spring is under tension, but properly covered and controlled is no big deal.
The SE oil ois a 15 wt and the stock is a 5 wt oil. Yes it will stiffen it quite a bit. I did it on mine and it was an entirely different bike with the SE oil (NOT the racing SE oil). You may want to try the 10 wt oil first, the 15 is quite stiff.
Thanks guys, i put the non racing SE fork oil in, someone had suggested to add 1/2 oz more than required, i did do that as well, they are just like i wanted, stiff, it's a good thing !