OK guys. I honestly don't understand what's the differences even though ice tried researching.

Its for my 2000 honda civic si. What I have is DC header and intake. Pretty much all of it.

So what's the differences between the two; spec d high flow cat and a test pipe?

High flow cat:
http://www.google.com/imgres?imgurl=http%3A%2F%2Fecx.images-amazon.com%2Fimages%2FI%2F41i73e3N1eL._SY355_.jpg& imgrefurl=http%3A%2F%2Fwww.amazon.com%2FHonda-Civic-High-Catalytic-Converter%2Fdp%2FB0087GRB1K&h=355&w=355&tbnid=Ii3z zTPPfdae-M%3A&zoom=1&docid=O01AV9D4985dLM&hl=en&ei=qOF_VNaA HIaYyASvt4HoAw&tbm=isch&client=safari&ved=0CB4QMyg BMAE&iact=rc&uact=3&page=1&start=0&ndsp=6

Test pipe:

http://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.jscspeed.com%2Fimag es%2Fcatalog%2Fcategory21964_thumb_full.jpg&imgref url=http%3A%2F%2Fwww.jscspeed.com%2Fcatalog%2FHond a_Acura%2F96_00_Civic%2FExhausts_Headers%2FBlox_Ra cing_Telescopic_Test_Pipe_for_96_00_Honda_Civic.ht ml&h=400&w=400&tbnid=FnEcXq5orkkLDM%3A&zoom=1&doci d=FW33NpzOGKVnMM&hl=en&ei=COJ_VL66OY_4yASmmYDgDA&t bm=isch&client=safari&ved=0CC0QMygRMBE&iact=rc&uac t=3&page=2&start=8&ndsp=10

Edit: sorry about links. I'm in mobile so it's hard to insert photos.

 

The Spec D isn't a cat, it's a resonator. It came with the spec d exhaust. It's essentially a test pipe but opens up a little with a holed pass through pipe going through it. It doesn't act as a decent cat so I wouldn't even call it a cat. They do as a marketing gimmick.

If you want a quality high flow cat that bolts right up, look into these guys:

Home - Random Technology

They make a quality high flow catalytic converter. One user who has their cat has had it for 10 years and still no problems.


As you can see in this , it's a test pipe not really a true catalytic converter.

Also of note, one of the stipulations for a tech thread in this forum is that you provide your full car information so everyone knows what we are dealing with and talking about.

Year, Make, Model, Trim and any Mods. Please fix up your first post with this information lest the thread be locked up for non compliance.

 

Edited my post