I know nothing about using a spacer when the likes of a non-standard sprocket is fitted.....(??), never heard of this, when I fitted the 43 tooth Renthal sprocket I aligned the adjustment marks as per usual the exact same on each side etc, simple job.
Regards speedo;
At around 35-65mph it's out about 5mph, and around 80-100 it's out about 10mph, I've a Garmin sat-nav fitted so I can see exact speed etc. I really doesn't bother me personally, much improved grunt/snappy power is lovely, it totally changes the bike, I utterly love it!
I've owned my V-Strom DL1000 over three and a half years now, so I know it inside out, I should have done this slight upgrade years ago.............been missing out regards the fun factor it seems!!!
Ye - Ha