Should I go with a 3in ceramic or 2.5in spun metallic cat? Which would flow better? I'm trying to stay within a budget.

 

Would the rest of the exhaust be the same size? as in you'd do a full 3" exhaust if you went with the 3" ceramic or a full 2.5" exhaust if you went with the 2.5 metalcore?

 

If I use a 3in cat the rest of the exhaust would be 2.5in.

 

Metal above ceramic. Get a 2.75 or 3" metal core.

 

but metal core are more than twice the cost.

 

If cost is a concern and if for ceramic, why not stick to what you've got?

 

because I don't have one yet!! putting my exhaust together this weekend.

 

I think spooky means stick with the stock cat.

 

Wait another week and go with the 3" metalcore. Do things right the first time. That's the cheapest way.

 

I of course agree with Paul, but I'm pretty sure the magnaflow 2.5" and 3" spun metal core cats use the same sized core.

 

Avoid the cheap ceramic "Magnaflow/Catco" cats. They'll get you through the visual inspection, but good luck with a sniffer test after the first ~year.

 

The metal core is going to get you proper emissions AND better flow. In the scope of the project is another $40-50 really that much dough?

 

Magnaflow Part# 53009 Catalytic Converter-Universal
3" In/Out No Air
$65.51

Magnaflow Part# 54959 Universal Spun Ceramic Catalytic Converter
3" C/C
$85.62

Magnaflow Part# 59959 Universal Spun Metal Core Catalytic Converter
3" In/out Center / Center
$102.76

Just do it.....thats a $40 difference over the standard lame cat, only $17 over the spun ceramic.

 

All the (tree hugging)cool kids are using the 3" spun metal core

 

I have a second chance offer on a Random Technologies 3in for $60 shipped, they retail for around $220 and are rated for 570cfm.

 

are the cores even different sizes on the 2.5 and 3" ceramics? cuz I dont think so.

 

Are you saying the cores are the same size just with different size inlet and outlet?

 

This is quite common, actually. It's much simpler for the manufacturer to only produce a few different cores, and use those as the basis for a large number of different packages.

The key point here is that the rest of the system is going to be 2.5". That fact alone dictates that the cat should have 2.5" I/O as well, regardless of what material the core is made of.