[allblackcoupe]

Is there a big difference between HFC and catless on a n55? Catless is like half the price so I’m leaning towards there. And does anyone know how to remove CEL after installing a catless? Does a HFC cause CEL?

[Eddien123]

Originally Posted by allblackcoupe

Is there a big difference between HFC and catless on a n55? Catless is like half the price so I'm leaning towards there. And does anyone know how to remove CEL after installing a catless? Does a HFC cause CEL?

Catless will usually let more airflow as it's 100% unrestricted. HFC would be to pass emissions and as far as CELs, you'd want to pair a tune with any cat modification as it's kinda pointless without and the car will just throw a CEL. A tune can also code out the CEL.

Edit: as far as I know, a HFC doesn't 100% guarantee to not throw a CEL as it doesn't clean the air as good as stock cats, but I know they don't usually give you any problems.

Honestly if you don't have to do a sniffer test for state inspections, just go catless as it's cheaper and can give more sound and power.

[allblackcoupe]

Originally Posted by Eddien123

Catless will usually let more airflow as it's 100% unrestricted. HFC would be to pass emissions and as far as CELs, you'd want to pair a tune with any cat modification as it's kinda pointless without and the car will just throw a CEL. A tune can also code out the CEL.

Edit: as far as I know, a HFC doesn't 100% guarantee to not throw a CEL as it doesn't clean the air as good as stock cats, but I know they don't usually give you any problems.

Honestly if you don't have to do a sniffer test for state inspections, just go catless as it's cheaper and can give more sound and power.

I appreciate the feedback. Will a catless add any hp/torque without a tune?

[Eddien123]

Originally Posted by allblackcoupe

I appreciate the feedback. Will a catless add any hp/torque without a tune?

I'm not 100% on this but I believe if anything it'll be a negative since the ECU won't know how to correct for the bad O2 readings it defaults to a richer mixture and you get worse fuel mileage and worse performance. There's no point in going catless if you don't plan on tuning.

[Munchi435i]

Yes it will increase flow and even without a tune, you'll notice a bump in performance. Meaning the turbo will spool quicker and throttle response will also increase. Actual HP increase I'm not 100% sure of though