Hi,
Your cats melted cause the pipes get so hot by the Heads when the silencer baffles are still in place.
Drilling out those two silencer restrictors cools the whole lot down. There is nothing wrong with the full open Air Filters, I have a Kuryakin chrome fully open one. We have driven in monsoon rain across UK and Europe, the engine never misses a beat.
Rgds
ian
+1
