only way you'll compete with the mustang is to supercharge the Zed,
if you want to feel faster under acceleration then lots have commented positively on the throttle controller, won't give more power but does make the throttle more responsive.
if staying NA then a remap will help but if you want to make the most of it you'll need to spend a bit in the first place doing exhaust, plenum spacer y pipe de cats etc
by the time you add all that up you might as well look at the super chargers. you'll get more power straight off, as NA modding won;t make a massive difference unless you spend mega bucks; which defeats the object when you compare it against the super charger.