1990 Isuzu Trooper with headers

I inherited a 1990 Isuzu trooper II that has an oversize cam with headers. since it is from Kentucky there are no emission laws. I live in Pennsylvania and am required to have a catalytic converter. If I install a catalytic converter will it hurt my headers or engine. Sorry if this has already been covered I could not find anything about it using the search function. Then again i am new to the community so any help you can provide me would be greatly appreciated.