Hello all my amazing mustang people! So I was wondering, im pretty sure the 03 gt I have has four cats on the exhaust, I live In Colorado and I’m pretty sure the state is sort of like California with the laws. I was just wondering if there is any possible legal way to remove any of the cats? I’ve looked everywhere online about it and it always just pops up that it is illegal to drive without one, and that it can’t put out more emissions than factory, can I not like get some very good cats in the front and just take the secondary set off? I’m pretty sure there are no o2 sensors after the second set, so it wouldn’t throw a CEL or anything like that, I’ve been wanting to snatch a bbk x pipe or something like that but that also gets rid of the cats, just want to really hear that v8 growl and rumble ya know? not trying to put glass packs where the mufflers are and straight pipe the thing lol, it’s just In my opinion the stock exhaust is super restrictive and very sound deadening and honestly like I said in my own personal opinion i think it’s kind of a let down, I mean four cats and 2 inch piping will do that but I’ve seen some very very crisp and nice sounding 2 valves so i know it’s possible, just don’t want to move states just to enjoy my vehicle
Exhaust
- Thread starter Domkami
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Lol but If I really need too, I’ll just get my emissions done and then take the cats off somehow, I’m not necessarily in a position to install an exhaust system by myself so I can’t do it without having a shop do it, but like I said the laws here are like cali so I don’t think any shop will touch my car with a ten foot pole if I walk in asking for that lol
Ok, let's do away with some 'old wife's tails'
You will not get a reputable shop to remove the cats unless they are replacing with new cats.
Deleting the cats will turn the CEL. And they have no effect on a stock performance.
What is the goal for removing them?
Oh, and post some pics of this fine piece of automotive machinery.
You will not get a reputable shop to remove the cats unless they are replacing with new cats.
Deleting the cats will turn the CEL. And they have no effect on a stock performance.
What is the goal for removing them?
Oh, and post some pics of this fine piece of automotive machinery.
Put a set of CAT Back exhaust on, like Borla S Type, if you want noise and clearer exhasut. As for the removal, don't, and as mentioned, will throw codes etc. You won't gain much of anything without them, but he CAT Back system will free up flow and give you the "noise" you want. Also, the primary CAT does the work and the secondary CAT monitors to see that #1 is doing it's job.
Thank y’all for the input! I’m trying to really learn this thing so I appreciate it a lot! I’ve got basic bolt ons, throttle body, plenum, cai, just recently grabbed a new intake manifold the is a little more reinforced cause I heard the oem will eventually crack, but this gt only has 40k miles, but my goal for this car is just to have a great time in it, I don’t really know how to explain it but I just love cars, love working on them, love driving, love everything expect the part where it takes all my money lol but I just want to have something that just feels like it’s really hot some kick ya know? I’m not trying to ever push more than like 400 to 500 hp on this motor to be honest, if I wanted something crazy I’d just drop a coyote in it lol, I also want it to be one of those cars you will hear while you are sitting in your house and you just be like, damn that thing sounds nice, I don’t know, like I said it’s got very low mileage only 40k it’s a convertible, got the mach audio, want it to be something sort of unique to be honest, I never see any built convertibles let alone a new edge Convertible, ( besides the svt)
And can I just say how awesome this place is, I’ve never really had anyone to ever talk to about car stuff like I would on here, like everyone always cares and wants to help another mustang owner, and it’s absolutely amazing, lol nobody has ever asked me for a picture of my car or anything so it honestly means a lot to me that y’all care to see it! I think it’s a beast lol just want it to feel like one too, got the metallic silver finish with the black drop top, and some American Muscle rims that fit perfectly with the car, I love it
To get that much HP you're going to go with a supercharger setup if you want to stay "smog legal". Any aftermarket cams, etc. are going to void all of smog. Changing the exhaust CatBack will allow you some noise and performance along with changing rear gears (auto or manual?) to "wake" the performance out of it. Other than that, you're staying pretty stock. If you ever decide on a Coyote, be prepared for a $$$ shock and keeping it legal.
It is an auto, and I’ve grabbed a pair of 4.10’s but I’ve seen online that they can get scary so I haven’t installed them yet thinking about snagging a 3.73 gear, But to the FI part, why are way more people choosing the supercharger rather than say a single fat turbo? Do superchargers just work really good with the car?
And just a supercharger wouldn’t put me at 400whp would it?
One of the few things I know little to nothing about is forced induction and I just want to make sure but is it safe / a good idea to supercharge this motor?
And just a supercharger wouldn’t put me at 400whp would it?
One of the few things I know little to nothing about is forced induction and I just want to make sure but is it safe / a good idea to supercharge this motor?
If you can find them, you can use hiflo cats. If you put on an off-road pipe you can get a tuner to turn off the rear O2's. You would have to swap it out to get your emissions check. A performance shop will do that for you usually
Stock exhaust system is 2.25" and most aftermarket exhausts start at 2.5". On a stock PI GT you won't get much of a HP gain changing to a 2.5" exhaust unless you go with something like long-tubes. Just want to manage expectations here. You can drop $1K on a nice mid-pipe and cat-back exhaust and you might get 5-10HP on the dyno on a stock PI4.6.
The cats arent as restrictive as everyone thinks. Again, on a stockish car, you might get 3-5HP if you remove them.
Most folks change the exhaust for sound. The stock-cat back is pretty quiet. Leaving the stock mid-pipe alone and just changing the cat-back might get you to where you want to be without ditching the cats. Or it might not and you can explore changing the mid-pipe out after. Some folks like mild, and some like it very loud. You will need MIL eliminators to avoid the check engine light as eliminating the cats will cause the CEL to come on. You will not pass a state OBD check as monitors will not be complete with them, so if you need to pass an OBD test, you might not be able to without cats.
Cats are federally controlled emissions equipment, so it's illegal to remove in all 50 states. However, not all states inspect and enforce them, which is why some states it's easier to get around these laws, and some like CA it's impossible.
If you do decide to remove the mid-pipe, keep it. If you sell the car, it might be easier to sell with the stock pipe if your state requires emissions testing. Those pipes are getting harder to find because everyone pulls them off and scraps them
The cats arent as restrictive as everyone thinks. Again, on a stockish car, you might get 3-5HP if you remove them.
Most folks change the exhaust for sound. The stock-cat back is pretty quiet. Leaving the stock mid-pipe alone and just changing the cat-back might get you to where you want to be without ditching the cats. Or it might not and you can explore changing the mid-pipe out after. Some folks like mild, and some like it very loud. You will need MIL eliminators to avoid the check engine light as eliminating the cats will cause the CEL to come on. You will not pass a state OBD check as monitors will not be complete with them, so if you need to pass an OBD test, you might not be able to without cats.
Cats are federally controlled emissions equipment, so it's illegal to remove in all 50 states. However, not all states inspect and enforce them, which is why some states it's easier to get around these laws, and some like CA it's impossible.
If you do decide to remove the mid-pipe, keep it. If you sell the car, it might be easier to sell with the stock pipe if your state requires emissions testing. Those pipes are getting harder to find because everyone pulls them off and scraps them
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