I'll try to help here. I have run Smarty for three weeks now on level 9. Moved up to it after running an Edge EZ for about 18 months. I have a 3" straight thru muff.
Power - 'rumored' and dyno proven about 60ish (don't quote me) but the real difference is in SOP and INSTANT spool. Throttle response like you won't believe. Words do not describe what you'll feel coming from stock to this... ... ... ... .
Changing levels - yes, you have to plug it in and not be driving/engine not running.
Smoke - none that I can tell, at least no more than stock or an EZ like I had.
I love it so much that I'm not even sure I'll add injectors... ... ... ... ... . well, that's misleading. I'm doing sticks next but now they will be smaller than I originally intended.
Hope this helps.
PS - I'm not being paid to say this - but it meets all the hype and then some.