Those calipers in the kit won't do anything special or improve braking, they're still a regular single-piston caliper like the factory installed. They're just painted red. Unless your calipers are in bad shape and beyond help, there'd be no benefit to installing them.
The cross-drilled and slotted rotors won't help either unless you're track racing at high speeds where you have to brake hard enough that it turns the rotors cherry red. The holes are just there to add to the surface area to help them cool faster. The holes also reduce the swept brake area so the holes can actually reduce their braking ability. The slots are just there to help vent gases that are off-gassed when the pads get red hot. Modern pads don't off-gas so that slot is just decoration. Such rotors will NOT help improve braking with normal daily driving.
The pads are nothing special either.
What I'd do is just get the Black Magic kit which includes Black Magic's pads and Centric Premium rotors. Black Magic pads will brake your Jeep better than any pad you can buy, they produce dramatically better braking. I've been running Black Magic brakes for probably 14+ years now, they specialize specifically in Jeep brakes. There is NO ONE that provides a better brake kit than Blaine Johnson does who founded the company and also developed the Big Brake kit (which uses dual-piston calipers) sold by Vanco PBS. Blaine is a developer/guru of Jeep products and knows more about Jeeps and Jeep brakes than anyone.
His pads alone will provide startlingly better braking. Combined with Premium Centric rotors available in his kit, you'll have noticeably and dramatically better brakes.
www.blackmagicbrakes.com