So Ive heard of a lot of people going 2 up in the rear and 1 down in the front and finding a new passion for there bikes. Is this a 520 coversion kit? If I want to go 2 up and 1 down what do I need? I know nothing about chains and sprockets, all I know is to lube mine all the time and adjust accordingly. How much does it change the bike...Ive heard a ton, true? And you must lose top end pull right? How much?