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Discussion Starter · #1 ·
Hello Folks!
I have a 2014 fist and i want to get rid of my stock cat and replace with either a 3'' DP or gutted cat with stock DP.
Listing my mods might help.....

1.muffler and res deletes to strait pipe( stock diameter)
2. mountune 215 kit with CAI
3. brisk racing sparkplugs
4. soon a snow water meth kit which adds 25 hp max
other little things

I want to rid the cat to get better airflow but the rest of the exhaust is stock. There is a company depot racing that says their 3'' dp will fit to the stock exhaust but I dont like the price and the look of not having a cat! I will use a spark plug defaulter to trick my rear sensor so a retune wont have to be done and actually isnt even possible with mountune files. My idea is to hollow out the stock cat and re attach the dp. The rest of the exhaust is stock diameter so im not sure if a 3'' dp to stock will do anything to release restriction if there is any without the cat. There is an elbow at the end of the dp that looks restrictive! MY QUESTION IS... does the stock downpipe have any restriction points beside the cat? The thing to think about is if the bigger downpipe is even worth it considering it is hooking to stock diameter exhaust (Minus the muffler and res). I hate my cat and want more pops and much more flow but to keep the rest of the stock exhaust because it flows fine as we all know! what would i benefit or loose by getting rid of the cat in general? I am doing this to prepare for my water meth kit. Im sure the car will benefit from no cat but it all comes down to the 3 inch dp or hollowed out cat. Which is best? keep in mind visual inspection. I rather fool them into thinking it is there rather than have a shinny new dp without a cat shell. I could probably weld the old shell on the new pipe for visual inspection!!
Comments from people that have experience with this or knowledge about fist exhaust is appreciated most!
Thanks guys for the help!! If you rather private message that would be fine too or email at [email protected]. Im just torn between the two options and not sure what each will do to benefit me
 

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You don't like the look of catless??? We'll just get a high flow cat (if which depo also sells) :). Problem solved. Manually tearing your OEM doesn't sound fun

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Discussion Starter · #3 ·
I am just concerned that at inspection a castles would look suspicious. my goal is to get rid of the cat all together.
 

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I am just concerned that at inspection a castles would look suspicious. my goal is to get rid of the cat all together.
They'll be able to smell it long before they see it. (Another reason you may want to look at high flow cat)

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Catalytic converters aren't as restrictive as people think they are. You might gain 3bhp total. The big gain is getting rid of that sharp, nearly 90* bend immediately after the turbo. You also want something that's a bit more uniform in size pipe wise instead of bottlenecks
 

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Discussion Starter · #6 ·
That makes sense actually! My girlfriends dad who owns a shop told me that he can pass me for not having a catles dp! If i get it inspected somewhere else i can just bolt the stock dp back on. Now i just need to figure out O2 sensor simulators. i am looking at a digital one and also a mechanical one that you screw on. what are your recommendations for these?
 

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2017 Ford Fusion Sport
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That makes sense actually! My girlfriends dad who owns a shop told me that he can pass me for not having a catles dp! If i get it inspected somewhere else i can just bolt the stock dp back on. Now i just need to figure out O2 sensor simulators. i am looking at a digital one and also a mechanical one that you screw on. what are your recommendations for these?
Either get a tune (tuners can turn off the o2 sensor check engine light) or a defouler. A quick search of Focus ST defouler should show you the way. Easy fix.
 

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Discussion Starter · #8 ·
Either get a tune (tuners can turn off the o2 sensor check engine light) or a defouler. A quick search of Focus ST defouler should show you the way. Easy fix.
A tune is way to expensive for me because i would have to buy a whole new access port thats $500. Here are my options...Magnum Bypass oxygen sensor simulator or Big Daddy cel fix. They clam that the digital version which is magnum brand is much more accurate and will also fix any issues with the upstream sensor due to more flow. I HATE THE COST OF THE DIGITAL VERSION!!AHHHH but the big daddy is much cheaper and acts just like a spark plug defouler. My only concern is that it wont be accurate enough. They say you need the digital one in order to equell them both out to work for more flow due to catless dp and more emissions etc.. I am absolutely confused and torn with which one to buy! what has worked for you man? This is so confusing and if you know anyone else with catless down pipe then please point them to this thread! BTW i appreciate everyone's help.
 

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A tune is way to expensive for me because i would have to buy a whole new access port thats $500. Here are my options...Magnum Bypass oxygen sensor simulator or Big Daddy cel fix. They clam that the digital version which is magnum brand is much more accurate and will also fix any issues with the upstream sensor due to more flow. I HATE THE COST OF THE DIGITAL VERSION!!AHHHH but the big daddy is much cheaper and acts just like a spark plug defouler. My only concern is that it wont be accurate enough. They say you need the digital one in order to equell them both out to work for more flow due to catless dp and more emissions etc.. I am absolutely confused and torn with which one to buy! what has worked for you man? This is so confusing and if you know anyone else with catless down pipe then please point them to this thread! BTW i appreciate everyone's help.
A TON of ST owners on here are catless. The two options (the ONLY two options I recommend) are to get a tune or get the defouler. If you don't want to go the route of a tune get the defouler here: http://www.focusst.org/forum/focus-st-performance/33006-defouler-who-using-one.html

Read that entire thread for some info
 

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Discussion Starter · #10 ·

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Why bother with catless dp and a meth kit if you dont want to tune? Seems silly to me.
 

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Why bother with catless dp and a meth kit if you dont want to tune? Seems silly to me.
He will have a tune "Mountune 215 kit with CAI"

However I think he will need a "retune" if he wants to see any gain at all from the Downpipe or the meth for sure. By default the 215 kit isn't configured for those so it'll hit a certain mark in power and stop the car from making any power over that.
 

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I went with the catless dp. Resonator delete. I left the muffler on so it won't that loud. Now we all want the sound. So I put a electronic cut out just before the muffler. Basically stright pipe. So I can loud when I want and quite when you need to be. Even with the muffler still on its still a nice sound when its closed.
 

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Ok first of all, im assuming you already have an accessport with a mountune tune if I read that correctly. If so, you do NOT have to purchase a new accessport if you want a new tune. I just bought one from stratified for $75 yesterday, so not expensive at all. Secondly, I installed a "j tube" o2 sensor spacer on my downpipe to prevent throwing a cel. It was $30 and has worked perfectly thus far. Lastly, trying to punch out or modify the factory downpipe sounds like a waste of time and money to me. Just buy a catless downpipe if thats what you want and be done with it.
 
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