Need help! Remedy for Borla Headers
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
High flow cats can be added to the existing X pipe for a lot cheaper that is going to cost for pick up a catted X pipe instead.
The high flow cats get added into the X pipe starting 3" past the point that the header flange connects to the X pipe, on each leg of the X pipe.
As for rear O2 sensors, they are already turned off in the tune, and really not needed since all they do is monitor the cats alone.
If rear O2 sensors are going to be added back in after the cats in the X pipe, then they will need to be installed in 90* anti fouling couplings, to pull the tips of the sensor out of the flow stream. Hence the high flow cats will reduce the emissions with a good tune to pass any smog sniffer test (maybe*), but since the high flow cats are mounted father down line of the stock locations, they are less effective than the OEM cats that the system is set to monitor the differential readings of the pre and post sensors instead.
* I state maybe, since it just depends on the stage 3 cam increased over lap/how much raw fuel its dumping into the exhaust system from idle up to start with.
Install location of where the cats needed to be added in.
The high flow cats get added into the X pipe starting 3" past the point that the header flange connects to the X pipe, on each leg of the X pipe.
As for rear O2 sensors, they are already turned off in the tune, and really not needed since all they do is monitor the cats alone.
If rear O2 sensors are going to be added back in after the cats in the X pipe, then they will need to be installed in 90* anti fouling couplings, to pull the tips of the sensor out of the flow stream. Hence the high flow cats will reduce the emissions with a good tune to pass any smog sniffer test (maybe*), but since the high flow cats are mounted father down line of the stock locations, they are less effective than the OEM cats that the system is set to monitor the differential readings of the pre and post sensors instead.
* I state maybe, since it just depends on the stage 3 cam increased over lap/how much raw fuel its dumping into the exhaust system from idle up to start with.
Install location of where the cats needed to be added in.
Last edited by Dano523; Aug 9, 2021 at 01:28 PM.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Measure the X pipe to know what size you need in ID sizes, then can find SS high flow cats as inexpensive at $50 each on amazon.
With then in hand, and since the X pipe should SS as well, muffler shop can cut the X pipe where needed, to weld in the set of high flow cats to the X pipe.
With then in hand, and since the X pipe should SS as well, muffler shop can cut the X pipe where needed, to weld in the set of high flow cats to the X pipe.
Melting Slicks
Joined: Nov 2011
Posts: 3,187
Likes: 266
From: Virginia
