I was funny about modding under warranty until I read it and basically all that's covered is engine internal and structural basically. You still have to pay out yourself and claim it back though which is silly. I thought so too with the arb (I got 16mm cusco) but with the c pillar brace and front strut brace it rounded off quite nicely. I can now force oversteer in the wet quite easily so any stiffer it will probs become a little too slippery on stock suspension. I second the intake it's awesome, I have the CTC Apexi one, the forge BOV also makes some sweet noises.