I fitted an unrestricted header and a shorter see-thru muffler to my Lean Burn AVL 2006 Electra X, (you can't get less restrictive than this).
I also fitted a K&N air filter in place of the standard one to assist with flowing more air into the 29mm CV carb,and also removed about a third of the airbox baffle plate.
After a lot of messing about I managed to compensate for these changes by fitting a 120 main jet, removing 0.8mm off of the bottom of the slide and by raising the needle to it's highest position .
On UK unleaded (95 RON) petrol these setting worked fine; providing a much higher top speed along with better mid range acceleration.
However these changes were also done in conjuction with cleaning up the cylinder head ports.
Hopefully this may provide a good baseline and save you some time should you decide to alter things.
I have recently changed over to a 32mm carb, kept the same exhaust set-up and am now running on a 130 Mikuni main jet, (200 Amal Equivalent).
From a personal point of view the top speed gain made from fitting the larger carb over the modified and re-jetted CV (paired with a free flow filter) does not seem worth the extra outlay if you compare the cost of one new main jet against that of a complete new carb