Some have had good luck with the Dynatek, Me... not so much. Im one of the many that got stuck with the notorios "popping, missing and sputtering" that the Dyna ECU's for the 700's are now known for.....
Im swapping out for a VDI unit which seems to be a much more reliable unit along with bein able to be tuned for any engine build/mod, including larger injectors.
First i would definately go with some type of Sheave/clutch combo... Unleashed's combo seems to currently be one of the most complete kits out there which includes the fix for the "melting slider" issue on the 700 clutches.
As for exhausts theres not really much to compare... no one is currently using the 700 to its full potential due to lack of correct fuel issues so you cant really tell a noticable difference between exhausts IMO