I honestly should have started a new link in the carb section. This site has more links and videos.
http://www.hpracedevelopment.com/sti...ing-block.html
That being said the STIC metering block does work! I attribute this to two issues. 1) I think it does a much better job of fuel atomization which allows the engine to more easily ignite and burn the fuel charge over a wider range of air fuel ratio. 2)Many older PWK carbs have worn needle jets which are not replaceable on the PWK. The needle jet is the metering orifice the tapered needle moves inside of and eventually wears over time.
I know how to jet a carb and I can honestly say this STIC made a noticeable difference across the board on my bike. Check out the Thumpertalk link and other STIC inks.