Review on NIBBI Racing Parts: High Performance GY6 Intake Manifold Boot for 125CC & 150CC GY6 Engine Scooter - Replacement Edition by Jim Ball

Runs flawlessly on 50cc 139qmb shortbore engine. I installed a large diameter 72cc kit. See, but left the stock head. First I installed a 5 hp Briggs carburetor. I switched to a Nibbi carb, a 24mm carb I think and after changing the supplied injectors the speed went from 23.4 mph to 34.3 avg (remember the Briggs carb) . I highly recommend using the full range of chokes, cables, carburetors and intake. I found a $24 k&n air filter that fits here perfectly. It has impressed everyone who has ridden it and I have put over 1000 miles on it with the port kit and Nibbi intake system. The only thing that has changed is the location of the nipple that attaches the vacuum from the head, changed sides and I had to remove the small plastic cover over the timing chain tensioner, that's all. But it has shortened and tidied up the look of my bike. Great solid products from nibbi and I too have received multiple packages in less than 24 hours using Prime. But they were only sent from one state. All packages were received from them in less than 48 hours.