Hi, Guest
the reason ford opted for a cat forward design over an undercar cat like used in pretty much all other cars is how QUICKLY the cat heats up.
the closer to the exhaust ports the faster it heats up, the quicker it gets to cleaning the exhaust gases.
i run an undercat cat right now and have the same emmission levels around a normal Focus even begin fiarly highly modified.
where the cat is placed has little do do with how well a cat works as a cat will work, although in a minimized capacity, when cold. they work best when HOT, which is why most good Automotive fix-it shops will tell you to keep your foot on the gas while in line waiting for emmissions testing to keep the cat hot and never to turn off the car.
the downside to a Catforward design is that in racing or extended spirited driving the cat can actually overheat and blowout... this will happen with a stock or a aftermarket high flow Cat replacement.
i believe ZX3Canuck has been through a couple of cats thanks to trackdays! ;)
the closer to the exhaust ports the faster it heats up, the quicker it gets to cleaning the exhaust gases.
i run an undercat cat right now and have the same emmission levels around a normal Focus even begin fiarly highly modified.
where the cat is placed has little do do with how well a cat works as a cat will work, although in a minimized capacity, when cold. they work best when HOT, which is why most good Automotive fix-it shops will tell you to keep your foot on the gas while in line waiting for emmissions testing to keep the cat hot and never to turn off the car.
the downside to a Catforward design is that in racing or extended spirited driving the cat can actually overheat and blowout... this will happen with a stock or a aftermarket high flow Cat replacement.
i believe ZX3Canuck has been through a couple of cats thanks to trackdays! ;)