Invidia Down Pipe w/High Flow CatINVIDIA FRONT PIPE The factory exhaust will always have restrictions and these restrictions are normally highest near where the catalytic converter is found. Invidia Exhausts use a larger pipe diameter and smooth bends which allows exhaust gases to pass with fewer restrictions and turbulence. A High Flow catalytic converter is then utilised to still control emissions for street driving legalities but with minimal impact to exhaust flow. In some cases