I recently had my 1997, 148,000 mi. 4.2L V6 engine rebuilt and want to replace all my cats as well. Should I replace with straight pipe, aftermarket cats, or ford replacement cats? I was just quoted this from my local ford dealer for the parts only:

F8UZ5E212AC, left drivers, double cat, $810
F8UZ5E212CA, right pass, double cat, $950

I think it is OBD2 because it was made after 1996. Does this mean that I will have computer trouble if I replace the cats with straight pipes?

Will I have the same computer trouble if I replace with $100 per side aftermarket cats? Which brands do you reccommend?

I also appear to have 2 oxygen sensors in front of the cats and 2 more behind the cats.

Thanks! -Ray