Hi mumra06. Welcome to BT!
Before I spent the money to upgrade the calipers, I would go the cheap route and invest in new pads. Even entry-level brakes these days are a considerable improvement over what was on the market just 10 years ago. One of the ways that manufacturers keep the cost of their brakes down is by specing low-cost pads which, IMO, is counter-productive.
Find yourself some new pads from Jagwire, KoolStop, Shimano or other name-brand and give those a try.
I'm sure that your braking performance will improve but, if not enough to suit you - then consider the calipers to be the culprit. Your new pads can be saved as replacements for the new brakes that you buy.
PS: Even before I swapped pads, I would make sure that the current pads are adjusted properly for height and toe and making solid contact with the braking surface of the rim.
Wheelies don't pop themselves. (from a QBP fortune cookie)
RobAR, thank you for the wise advice. I will most certainly start with brake pads! I'm hoping they will solve my braking issues.