Personally I put a tiny amount of thermal paste that's used in electronics between the wheel and the rotor.
This serves a couple of purposes.
1. It stops any corrosion between the two surfaces as it keeps all the water out.
2. It assists in the heat transfer between the rotor and the rim reducing the rotor temp.
The rim is one massive aluminum heatsink. The stuff I use is the cheaper White version NOT the really expensive Silver one that actually contains a lot of silver (the best heat conducting metal there is). The Silver one is used for CPU's in your computer and is extremally thermal conductive.
Before you go off and say that it affects your tire pressure, probably not on a 19inch multispoke forged rim, there is just not the section of alloy to conduct the heat right out to the tire and remember those spokes are spinning at high rpm through the air and are being cooled rapidly.
Nothing wrong with the stock single piston caliper, its all about the pads and the size, material and design of the rotors.
Considering the size of the stock i30N rotors are the same diameter as my stock WHEELS on my old car, I'm not anticipating any issues.
Advantages and disadvantages of multi piston calipers. Sure when everything is new, in theory the multi-piston will give you more even brake pad wear but besides being more expensive, if poorly maintained without fluid changes individual pistons can stick and you are no better off.
If I ever see the need you can simply move to a track focused front pad for the i30N here.
Genuine Hyundai Parts & Accessories. Hyundai spare parts, merchandise and N Performance parts.
parts.philgilberthyundai.com.au
i20N here.
Genuine Hyundai Parts & Accessories. Hyundai spare parts, merchandise and N Performance parts.
parts.philgilberthyundai.com.au
Rears also available, what else do you need.
Nothing wrong with the stock set-up, you must always remember to run in any new pads with about 300km of "Normal " driving before trying to race on them.