I was looking on eBay and found a high flow cat test pipe but aren't they two different things? And will either one pass emissions in tx?

 

Test pipe eliminates cat. Won't pass anywhere. High flow cat eliminates some back pressure. I have a Magnaflow high flow cat on my Accord and passes emissions.

 

Yes they are two different things. High flow cat still contains a catalyst and it is a catalytic converter. Where as a test pipe is just a straight through resonator.

Whether or not the high flow cat will pass emissions depends on it's design and your state emissions standards.

 

many of the "high flow" cats on ebay are just test pipes.

 

x2

Should go with a known brand that has quality parts. Magnaflow and Flowmaster both make universal high flow catalytic converters that can be fitted to any vehicle. Most exhaust shops can weld them in easy enough. If you can weld then you can save some labour costs.

 

Can you look at the two and tell the difference? Is it the honeycomb thing inside like regular cat?

 

Yes a high flow cat will have the honeycomb in it. A test pipe is usually just a resonator. It will have rows of holes along the pipe wall. This is only there to cut down on some exhaust sound.