Re: more top end speed after run in
I have had kits that ranged from 25 mph (40 kph) to over 35 mph (60 kph).
A lot depends on the engine, which intake it has, how well the ports are matched, what type of muffler, ect.
Most all of them can be made to run 50-60 kph with a little work.
Break-in does help, but I think a lot of it is due to "tweaking the engine and components" during the break-in period.