Guys, I just completed the valve opening mod and it's a nice improvement in sound. It took me about 30 minutes all in and I can notice the difference, especially at lower RPMs. If I can swing another 8-10db via some other mod, the exhaust would be perfect! My butt dyno also noticed a slight increase in response at lower RPMs, but that could be in my head...or butt.
Thanks for the detailed explanation!!