It's moreso the extra cost and scrutiny the mod will go under because you have brackets. They'll make you do hard stops from 40-60-80-100kph (a couple of times I believe) to ensure your setup is working fine, i'm not sure how aggressive they are in terms of inspecting your parts. edit: The Viking told me it cost him $150 alone to have his modified brake setup on his Gen4. It consisted of Gen3 V6 Camry 2-pot calipers, a bracket and a 13" Supra rotor.