What's a good 50cc moped/scooter that's easily modable and fairly fast?

Recently an old moped I built myself with a friend has broken and I'm in the market for a new one. I need it to reach speeds of 40-50 Because of the roads I use to commute and I like fast bikes who doesn't. I was looking at the Honda ruckus but I haven't heard good things about it being a good road bike, I need the bike to be able to make it across some main roads for a couple miles so if anyone knows if the ruckus is reliable at 40-50 mph please inform below. If anyone knows of any other models to look into that would also be appreciated.

State or country you plan to ride in? UK seems to have a minor loophole for Mopeds made before sometime in 1973- no speed limit until then, just engine size and pedals--The old Puch riders can legally do more than 30 mph with the old frames as a unrestricted whatever and Moped Army site has more details. Last week was a post about a 50cc 'motorcycle' made in Indiana that could do better than 30mph- looks like a water cooled dirt bike engine in a 'retro' frame and capable of advertised 60mph- sort of like old Kriedler. New Kymco People model is made for some unrestricted markets and does about 45- it has a simple electronic control box for restricted markets, remove it and do 45mph again but don't get caught by police and mouth off saying the officer can't do anything to rider for doing speed limit- BUT false 'Moped' plates, no motorcycle endorsement, false application of state license documents may mean a overnight in jail and $1000.00 cash bond to get out. Your age and license status?

Get a 2 stroke they're easy to mod, I have a Yamaha jog r and its putting out 50mph with just a sports exhaust

To meet the laws regarding 50cc mopeds, I don't think you will find a "fast" one, many laws limit the top speed of these 50cc bikes.