Dodgy secondary cats

DBE · 11-22-2015, 10:25 PM

Anyone had problems with your secondary cats?

Another member here had his car custom dyno'd and had dramas which turned out to be flow related caused by the secondary cats restricting flow as they were stuffed

According to his experienced tuner hes seen this a number of times before and believes the metal secondary cats arent up to the job

American Dave · 11-23-2015, 12:00 AM

I replaced the stock front and x pipe when I bought mine. Replaced with after market items and high flow cats in the x pipe only. Unleashed the beast in terms of performance once tuned for it.

DaveDee · 11-24-2015, 05:31 AM

Track (test) pipes are great as they get rid of the 400 CPSI ceramic, restrictive cats, problem is the secondary cats are just that. The higher temperatures and more extreme conditions will impact on cats that were designed to be essentially backup cats. If they fail, fall apart and get spat out the exhaust, even better but if they melt down and cause restrictions there is an issue that will affect performance.
A good design high flow (aftermarket) cat is designed to take the impact of being a primary cat.
Having tested both setups and supplied a number of each, nothing beats a good X pipe with high flow cats. The difference in a full replacement X pipe is obvious, even the tone and burble are better.

11-22-2015, 10:25 PM	#1
DBE First Lieutenant 31 Rep 308 Posts Drives: 08 E92 M3 Join Date: May 2012 Location: Brisbane iTrader: (0)	Dodgy secondary cats Anyone had problems with your secondary cats? Another member here had his car custom dyno'd and had dramas which turned out to be flow related caused by the secondary cats restricting flow as they were stuffed According to his experienced tuner hes seen this a number of times before and believes the metal secondary cats arent up to the job
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11-23-2015, 12:00 AM	#2
American Dave Captain 118 Rep 621 Posts Drives: 2008 Jerez Black E92 M3 Join Date: Oct 2014 Location: Perth Western Australia iTrader: (0) Garage List 2008 BMW M3 E92 [0.00]	I replaced the stock front and x pipe when I bought mine. Replaced with after market items and high flow cats in the x pipe only. Unleashed the beast in terms of performance once tuned for it. __________________ Jerez Black 2008 6MT with Borla Atak Exhaust/ M3 World X Pipe and Test Pipes/ aFe Pro Stage 2 Intake / 19" Advan DZ-DF Forged Wheels wrapped in ContiSport Contact 5P 245/35/19 Fronts & 285/30/19 Rears/ KW Var 3 Coilovers / BPM Sports Stage 2 Tuned/ VAC Rod Bearing Replacement / Throttle Body Actuator Gear Set
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11-24-2015, 05:31 AM	#3
DaveDee Major 532 Rep 1,464 Posts Drives: BMW X5M Comp Join Date: Oct 2010 Location: Gold Coast Australia iTrader: (0) Garage List 2021 X5M Competition [0.00]	Track (test) pipes are great as they get rid of the 400 CPSI ceramic, restrictive cats, problem is the secondary cats are just that. The higher temperatures and more extreme conditions will impact on cats that were designed to be essentially backup cats. If they fail, fall apart and get spat out the exhaust, even better but if they melt down and cause restrictions there is an issue that will affect performance. A good design high flow (aftermarket) cat is designed to take the impact of being a primary cat. Having tested both setups and supplied a number of each, nothing beats a good X pipe with high flow cats. The difference in a full replacement X pipe is obvious, even the tone and burble are better.
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