Hi-Flow Cats and Smog Check II

[Johann]

You folks out there in the PRK who have hi-flow cats, any problems getting through Smog Check II? What brand cats?
Has anyone compared their before/after tailpipe numbers, if so what were they like?

 

[Leonard Knight]

Not sure where PRK is but I am in Los Angeles county and I had the high flow cats on my 96gts from Random Technology and had no problem passing. Car was just as clean as with stock cats.

 

[Ulysses]

Peoples Republik of Kalifornica

 

[XS TORQ]

I have Hen-S-E high flow cats (plus headers and Borla 3" mufflers) and my car was just as clean this time as it was before having it done.

 

[VPRVENM97]

Here are my before/after numbers. With stock cats it was tested 3 years ago at idle and 2500 RPM. The high flow cats test was done last year under Smog Check II with the dyno at 15MPH and 25 MPH. I'll give you the 25 MPH numbers. Not really a fair comparison since one is done with no load and one with a load.

Bone stock
Smog Check (Dec. 01)
2500 RPM (no load), CO2=13.89, O2=0.0, HC=16(max 130), CO=.02(max 1.0)

K&N's, T&D's, 65MM TB's, Headers, High Flow cats, Corsa Catback
Smog Check II (Dec. 03)
25 MPH (on dyno) CO2=14.9, O2=.17, HC=14(max 35), CO=0.0(max .46), NO=107 (max 706)

 

[Johann]

Looks like one can have both higher flow and good emissions which begs the question: "Why doesn't the factory install better flow cats?"