Added this kit the other day to my CT70 clone with Piranha 140CC engine. Before adding the 146cc V2, I was running the 140 with a mikuni VM26 (195 main jet), 18 x 32 sprockets, and a really nice OverRacing titanium exhaust. Pre-146CC kit my bike, which I only use on the street, could slowly climb to at least 65 mph if I was in a full race tuck. After adding the 146cc kit my bike PULLS HARD at 55mph toward an as yet unknown top speed. This kit has definitely added horsepower and top speed. Glad I bought it.