If you go for an end can alone it will crispen up the throttle response a little, so it is noticeable, noise is lovely.
Decat and you're into a power commander and dyno setup, a must do for it to run OK and not cook your exhaust valves.
Exhaust servo valve eliminator needed, Air filter not really significant.
With an aftermarket can & decat setup you will get a stronger mid range, and ditto at high revs, to the extent of about 10 to 15%, that you will really feel!
Your into about 1000 pounds for that.
There is an airbox mod which helps that setup marginally, just a couple of holes in the right place.
Alternative is end can and a 'hilltop' setup, one or two members followed this route with good results reported, I can only back up the decat power commander etc route.
When I go abroad I just slip the stock end can on, and loose some top end, but its then socially acceptable to the frogs, and the fuelling is OK.