Cat for TH DP

[Ed Valvo]

Just bought a 3" cat for the TH DP from Ramchargers. The arrow of flow is backwards. It points from 4 bolt flange to the slip fit end. RC says it doesn't matter. It's interchangable. Does it matter?

 

[gofstbuick]

If it is a three way cat (TWC), then yes, I would think it would matter. Because a TWC performs reduction (controls NOx) first and any left over O2 is stored in the substate material and released during Oxidation (controls HC and CO). I would suspect that if it performed oxidation first, the byproducts (H2O and CO2) may split and under temperature will attach to the nitogen atom. But I don't know for sure.