So what can we expect with the STaSIS exhaust? Is it similar in sound to the Milltek? Deeper? Higher pitch? We all know STaSIS makes great products and I'm sure this exhaust is no different.

haven't heard the final version, when they did testing, I had the good fortune of being the test mule. The last version I heard was not like Milltek. It had a really nice low end burble (think from idle to 2000RPM), from there it smoothed out to a bit, but kept that low end without being droney. At cruising it is noticeable but not "loud". I would say a tad bit more noticeable than Milltek.

The only version I have not heard is the final version. I know they were trying to dial in the high end, and make it louder (I believe).

i.e. piping diameter, performance gain, wieght savings, etc...?

not sure of exact specs