service engine light soon is on

[bml]

Purchased an 01 gt in colorado-9000 miles. The car has a supercharger ,bigger injectors, bigger throttle body,larger fuel pump and custom burned chip. I drove the car from colorado to nebraska, ran fine till we reached my home. THe service engine light soon came on and I noticed a slight pinging or knocking. I had the computer checked and it had two codes po420 and po430 both said catalyst efficiency below theshhold bank 1 and 2. I think it had to do with the change in air from thin to thick. I also have high flow cats and 3in bassani exhaust. any help would be appreciated. bml