i was interested in getting the dc jdm 4-1 or the oem jdm 4-1. if i got a new 2.5" cat, would my greddy evo still be able to be used? are ther cats with a 2.5" inlet and a 2.25" outlet?

 

Ask the manufacturer or seller before you buy it. If not you can definetly make it work with some fabrication.

 

The cat normally used for this application is the 94006. It has a 2-1/2" inlet/outlet. The shorter 54006 could be used and a tapered cone welded to the outlet in order to reduce it to 2-1/4" OD outlet to match your 2-1/4" exhaust, but the 54006 doesn't flow as well as the 94006.

 

So what are these part numbers for? Universal or something? I'm needing the same thing soon.