My suggestion for the 24mm front bar was just to complement the GTR rear..but i looked it up and GTR rear bar is 25mm, (i thought it was 22mm), so would be better go the 27mm front.
"Rear-wheel drives that oversteer, or pick up an inside rear wheel and spin it, often benefit from a upsized front sway bar"
Maybe just start off with a thicker front first and see how it handles..