Help picking a cat converter

[CorvallisBMW]

I need to get an exhaust setup for the m30 swap. I'm pretty settled on a Dynomax VT 2.5" single muffler, the sound flap thing is way cool IMO and will fit the character i'm going for for the car. But I need a converter. Searching Summit for a 2.5" single outlet I get like 70 results, all about the same price ($70-90). So what the heck makes them all different? Is there a brand I should go with? Also, anyone know if it would be cheaper to fab the 2 stock downpipes as duals in to a dual-in, single-out cat or to merge the pipes and then travel in to a single-in, single-out cat? Thanks guys!

http://www.summitracing.com/search/Part-Type/Catalytic-Converters/Emissions-Legal/49-state/Universal/Yes/Outlet-Quantity/Single/Outlet-Diameter-in/2-500-in/?page=1

[nando]

I need to get an exhaust setup for the m30 swap. I'm pretty settled on a Dynomax VT 2.5" single muffler, the sound flap thing is way cool IMO and will fit the character i'm going for for the car. But I need a converter. Searching Summit for a 2.5" single outlet I get like 70 results, all about the same price ($70-90). So what the heck makes them all different? Is there a brand I should go with? Also, anyone know if it would be cheaper to fab the 2 stock downpipes as duals in to a dual-in, single-out cat or to merge the pipes and then travel in to a single-in, single-out cat? Thanks guys!

http://www.summitracing.com/search/P...500-in/?page=1

you don't need one with the air tube (those are for cars with dual O2 sensors), but I would reccomend not buying a cheap ceramic core cat. magnaflow makes a metal core version, you can also get a metal core from vibrant but it's probably a lot more expensive.

[FredK]

I would get a Magnaflow 59926 2.5" I/O metallic substrate cat. It has proven flow numbers, and IIRC is a 300 cell per square inch cat for decent sniff test results (if you need to pass them), and it's around $105.

I believe the Arvin Meritor Metal'Cat (not to be confused with the Metalcat from Australia) is a 200 cpsi cat, but I've forgotten if that's true or not. I run a 2.5" I/O AM Metal'cat.

[nando]

and FredK comes to the rescue with a part#. thanks Fred!

what really sucks are the metal core cats cost $10 more than the ceramic one I got. doh!

[CorvallisBMW]

Awesome, thanks Fred!