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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHMagnaflow High-Flow Cats
Leading reported evidence
Replace around the time the 996 rolled out
Suggestion or failed attempt
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Suggestion
All this changes around the time the 996 rolled out.
Leading evidence: 'Replace around the time the 996 rolled out' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace around the time the 996 rolled out' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
We use HJS 200 cell high flow cats which gaurantee no check engine lights but still 93-95% straight pipe.
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Suggestion · Original poster
Anyone use the Magnaflow High-Flo cats on their 996's?
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Anyone use the Magnaflow High-Flo cats on their 996's? I'm hearing a little rattle that might be a bad factory cat, so I'm weighing options for replacing them. I've read that there could be issues with throwing a code if you swap out the factory units, but there seems to be differing opinions on this. I have the Fister style mod on my exhaust, if that makes any difference but no other mods.
Nooooo! You only do that to cars that you don't care for. I've put non foulers in a couple project POS cars just to keep the light off but never in one that I want to keep. The non fuler will cause the secondary O2 to get a false reading and since this info is used for all kinds of things (fuel trim, etc.), you con;t really want to do this to a 996.
Scott from Fabspeed here, looks like you are having issues with your cats on your 996? Starting to see more and more of these circumstances as the vehicles are getting a bit older and the mileage is creeping up. We use HJS 200 cell high flow cats which gaurantee no check engine lights but still 93-95% straight pipe. Also just released, we offer a lifetime warranty on the HJS Catalytic converters regardless if tracked or street use!
Check out the Sport Cat X-pipe and let me know if you have any questions and for forum pricing!!
Fits all Porsche 996 Carrera vehicles 1998-2004
Greatly improve horsepower and torque by 25 whp and 32 ft-lbs
Saves 11 lbs from the rear of the vehicle
Proprietary Investment Cast X with tuned window was dyno developed to deliver huge mid range torque and high rpm horsepower gains
X-pipe design includes integrated 200-cell HJS Sport Catalytic Converters for maximum flow, efficiency, all while being able to pass tail pipe emissions tests (will not pass C.A.R.B visual inspection)
Constructed from T304L stainless steel tubing, mandrel-bent for accuracy and flow
To be clear Imo000, the secondary O2 sensor is an emissions system monitor. The primary O2 sensor is used to feed the ecu the afr readings for optimal engine performance. If primary O2 sensors are reading improperly, a code will reflect this.
That's how it used to be. The secondary sensors only monitored emissions and it was like this for a while. All this changes around the time the 996 rolled out. Although it still could be like that for some engines that are less performance oriented but not the M96. I'm pretty sure of this but then again, I could be wrong.
This is false. The secondary O2 sensor is only used to measure the effectiveness of the cat. A tune for the 996 will entirely disable the secondary sensors to prevent a check engine light and they can then be plugged as no sensor is needed.
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