The OEM shock is not sprung for your weight range, so it would squat in the rear while cornering or under hard throttle.
The OEM shock had low-speed compression and rebound adjusters, and you can tweak it to some degree, but beyond that, a better quality shock is needed.
Ditto for the forks, in that their springs will need to be matched to your weight and possible re-valved for better operation.
It's a fact of life that factories only supply suspension that's "good enough" for a rider of a certain weight range (around 150-170 lbs).
And if you that that's bad, for non-race replica bikes, it's even worse. They get truly abysmal suspension.