First, what is the MTA bike? Do you have any more information on it, or a link where we can read the stock specs?

If the bike is brand new, I would not waste money on replacing parts that are working fine at the moment. What I would do is find a pedal setup that you enjoy, and handlebars that you also enjoy. Along with these two, a saddle that you find comfortable. If you are not comfortable on the bike, replacing the crank/wheels/headset/etc. will not make any difference.