I'm amazed that the stock header pipe isn't the first thing to get the boot when getting an AVL to run like a 500 single should. As you have found out, spending hundreds of $$$/£££ on carbs and cams without sorting the exhaust breathing out is, frankly, money wasted. That poor bike has been waiting 9 years for this!
A sportier exhaust and carb will give you a better all-round performance, while the "S" cams will restore some of the missing top-end robbed by the stock AVL cams' tendency to cause valve bounce at around 5,800 rpm.
I also swapped my Electra's 18T countershaft sprocket for a 17T for a more responsive bike around town, and given that the bike felt over-geared before, there was no effective loss of top-end performance.
A.