Jul 19, 2019 · You probably got P0420 catalyst efficiency below threshold. I got the same thing on a BBK catted downpipe. Most high flow cats are 200 cell while OEM ones are usually 400 cell. Most …

Feb 16, 2020 · Metallic high flow cats have been becoming more popular recently. The two questions people usually ask are 1) which flows more? 2) On OBD 1 cars, will metallic substrate cats pass …

Mar 26, 2017 · Just curious about adding a high flow cat downpipe to my Civic Hatch but wanted to know since it still has a catalytic converter, will the vehicle be able to pass California emissions …

Aug 30, 2022 · Pass inspection with high flow cat? Jump to Latest 7.7K views 16 replies 5 participants last post by Buldawg76 Sep 2, 2022 Smokeyeco Discussion starter

Aug 28, 2025 · A larger down-pipe with high flow cat may provide the depth of sound you're looking for but may need larger pipes. All this requires better access to parts I suspect.

Sep 22, 2012 · Has anyone replace their cat with a high flow one? I am only going to to have one before my 02 and I was wondering if High flow cats would trigger any...

Jul 3, 2021 · Just installed a high-flow cat and did a full custom tuned since I'm now FBO. This is the first car I've had that I've gone this far down the rabbit hole with parts and especially a high-flow cat. The …

Jun 3, 2021 · Most high flow cats are 200 cell while OEM ones are usually 400 cell. Most high flow ones will pop the CEL. You should be fine to drive the car. You can get an O2 spacer for the downstream …

Feb 14, 2006 · Hi-flow cats don't really quite an exhaust at all. All of the ones I have heard sounded the same as before maybe a slightly different tone. Your not going to gain any low end torque with it over …

Dec 4, 2020 · The high flow cat has very little open space to deaden the sound and is half the size of the OEM cat so it really makes the car rumble on throttle. I am thinking about adding silencers to the …