It will be almost completely flush. Nhancedperformance UK quotes on their spacers page for the i20NGuys, what ET and rim size have you ordered?
I would like to buy: https://www.ozracing.com/alloy-wheels/oz-racing/i-tech/formula-hlt-5h
18x8. ET45 5x114,3. Not sure if they fit.
"Whilst we have a number of different sizes available, we STRONGLY advise 15mm Wheel Spacers for the i20N running 7.5/8J alloy wheels for the perfect fitment! " (https://www.nhancedperformance.co.uk/wheel-spacers-4-2632-c.asp)
So your 14.4mm would be perfect. honestly thinking of doing the same. Why not have a lighter, wider wheel which has sexier fitment. Sorry to bump