If anyone's looking to upgrade their brakes properly this data should be helpful. The N16 1.6 runs a single piston sliding front caliper. Front caliper piston diameter is 57.2mm. Rear caliper piston diameter is 33.9mm for ABS model and 17.46 for non-ABS (not sold by TCM in Malaysia)
Front disc rotor sizing is 257mm X 22mm Rear disc rotor sizing is 258 X 9mm or Rear drum 203.2mm inner diameter. My Bro Fooyc confirmed that the 1.8 XG-L runs similarly sized brakes as the 1.6. Master cylinder sizing is 15/16" or 23.81mm This compares very favourably to a Proton 1.6/1.8 which runs a 256mm X 24mm front and 260 X 10mm rear with same Master cylinder sizing is same. This data should be helpful if you're thinking of upgrading your brakes to 4-6-8-10 piston calipers. So long as you do not deviate 5-10% from the total piston surface area your master cylinder should be able to handle. The formula for piston area is Radius X Pi Squared if you need help on the calculations. This is gives a total piston area of 5139 square mm for the front calipers. Per theory, a sliding single piston caliper is always calculated as a twin piston.
I would suggest a caliper that does not have more than 5600 square mm surface area else the master cylinder would need to be upgraded to a larger diameter unless you have a fetish for dangerously long brake pedal travel. Leave the rear caliper alone. A FF car uses up 70-80% of it's front brakes leaving only the miniscule remainder to it's rears. Having said that I'm still gonna upgrade my crummy rear drums to discs. Looks loads better too.
I've researched and there's actually a few options out there in the US for the front big brake upgrades. This includes a Wilwood kit from Fastbrakes.com, Brembo stock B15 Spec V setup from G Spec Performance, humongous Brembo GT aftermarket setups (at least a 17" wheel is required) and Stoptech. All the mention supply aluminium 4 piston calipers with single piece or composite rotors, brake hoses and brackets to mount everything to the N16/B15's hub. Don't recommend the popular NX2000 AD22VF upgrade as the rotor is the same diameter. Only slightly thicker (26mm). DBA however does have a 4000 series application for that particular disc/rotor but none for our stockers. Bummer! More details in Mike Kojima's Garage
Before you do all this do ensure your tyres are grippy enough. It's the tyres that actually stop the car and not the brakes. If the tyres lose grip even a buzzillion pot caliper will not save you.