My bike is a 2002 SV650 naked model and I purchased my "Advancer Key" from a company JHS RACING in England: When you get to the site, click on "Tyres & Misc." and you'll find the key near the bottom of that page. If I remember right, I had to arrange the purchase via email and it arrived about three weeks after. Someone in the US is also selling one, but the price is greater (and may include the tool). Do a search on the SVRIDER.com forums if you're interested in that, I don't remember any details about it.
First, a disclaimer and a caution;
These photos should be considered to be only an additional helpful guide, to be used in conjunction with an SV650 shop manual. If you can't afford an official Suzuki manual, then there are copies available for download at SoCal SV-Riders. The section that applies here is "Engine", section 3. I highly recommend that you download at least this one section for reference in case problems arise.
Normal safety precautions should be observed and torque wrenches should be used to prevent stripping threads or breaking bolts. I've documented how I performed the work, and hopefully I haven't made any mistakes. These photos can be downloaded in a zip file on my Downloads page. The resolution is probably a bit better than what you'll see here.
There have been reports of the threads stripping on the rotor puller tool, causing the tool to get stuck in the rotor. This could be an expensive mishap, so use common sense, and don't "press on regardless". If something doesn't seem right. Stop and examine it. Consult the manual or someone knowledgeable.
An alternative to the "offical" tool is a high strength hardened steel bolt (thread 20 mm x 1.5). If you choose to try this, you will probably have to special order the bolt from a business that specializes in high strength fasteners.
Handle the rotor carefully. This item spins on the crankshaft at speeds up to 10,500 rpm and even the slightest damage would upset the balance and cause the engine to vibrate.
The advance key gave me a very noticeable boost in midrange power, about 2,000 - 6,000 rpm. I haven't had the bike dyno'ed, but you don't need a dyno to feel the extra torque. No other modifications were required. Premium gasoline is recommended.
Supplies & tools you'll need:
1) Gunk engine cleaner or equivalent
2) Electrical contact cleaner, or some other quick evaporating degreaser.
3) 8 mm socket
4) 10 mm socket
5) 12 mm open end wrench
6) 17 mm socket
7) 21 mm socket
8) inch-pound torque wrench (to 84 in/lbs)
9) foot-pound torque wrench (to 87 ft/lbs)
10) Rotor puller; Suzuki p/n 09930-304450 (thread 20 mm x 1.5)
11) New rotor cover gasket