My sway bar on my VS was plug and play with no mod needed. It has worked perfectly for 52,000 miles. I posted all about it here with brand and stock number.
I wouldn't feel safe without both a front sway bar and rear camber compensator installed. I'll bet a lot of VS are running around without either. I am always amazed at the low number of wrecks of Speedster replicas that have occured. I drive mine like it was my BMW bike---knowing that every other vehicle is out to get me! Which they are.