Which cat generally goes first?

Precat or Cat? 2000 TRD, 284,000 miles, both O2's are new, haven't thrown a code since replacing, but it is time to update...

Would like to do it one part at a time due to costs...

Precat or Cat?

Thanks

 

Buy one now Buy the second one when you can

Then install them at the same time

 

upstream one always goes before the downstream, it takes all the abuse.

 

That's what I thought, I have prepared everything by removing all the old rusted nuts and bolts between end of Precat, Cat, and rear exhaust section, and replacing them already, so this should be a piece of cake. The only nuts that could give me a problem are the three forward exhaust flange nuts to the Precat. I am hoping my torque adjustable hammer drill will vibrate those loose without breaking the studs after a good soaking. The rear O2 was a biatch, the nuts were really basically rusted away, but the studs were fine...

Thanks...Precat it is....