2015 -2021 WRX – Full 3 inch J pipe / Front pipe / Downpipe with Hi flow cat in one. This is one of the nicest pipes made for the 2015 WRX. This pipe connects to the Hotside of the Turbo ,when you remove the stock Cat, you allow the exhaust to escape without a bottle neck the turbo spools faster and enables you to make much more horsepower. This should be one of the first mods for this car.
The design on this pipe has purpose. Hi Flow Cats do not prevent Cel Lights( see below) the extended O2 bung does. So I located the cat by a heat shield in the location toward the center of the vehicle. Any restriction in an exhaust system like a cat causes higher temps I did not want this heat under the oil pan.
– 100 cell Metal substrate Hi flow cat
– 3 inch ID
– 304 stainless steel.
– 10mm flange
– Direct fitment
– Gaskets included
– Track / Off road use Only
This model also available in test pipe version, check out my ebay store.
Hi Flow Cat 101
ALL brands of HI FLOW CATS are not meant to clean the exhaust and pass emissions like a stock cat, they
would not be hi flow at that point. The goal is to knock out the gas smell and flow a ton of exhaust so you can
make good power gains like a Catless does. The metal substrate needs to be hot to do this, so all Hi Flow Cats
brands will have smell until the cat is warmed up.
As far as passing emissions and throwing a CEL code , all Brands will do this also. Just like a Catless pipe the
cars sensors will know the exhaust is not clean. This does not mean you can not get rid of the CEL and pass
emissions. For instance an Evo 8 ran a full 3″ catless exhaust, with a extended the O2 bung it kept the sensor out
of the flow of exhaust and with No CEL it passed emissions.
So with a Hi Flow Cat or a Catless you can trick the ECU by extending the bung, they even make O2 – 90
degree extenders now. Or you can have the tuner disable the secondary sensor and it will not throw a CEL. At the
end of the Day a HFC with only cut the gas smell ir wont stop a CEL any better then a Catless.
Some States ban the use of HFC or Catless pipes and they are only allowed for off road use. It is up to the user
to know his state laws and follow them.