Ive purchased a set of full length headers for my 2004 Mach. Ive been told that i can go catless when i get the O2 sensors needed for the headers, without the check engine light coming on or my car acting funny. If anybody has any info as to whether i for sure can go without cats,it would be greatly appriciated.

 

You can go catless and get a pair of MIL eliminators for your 02's and you wont have a check engine light.

 

in order to go catless...you need either MIL eliminators or a hand held turner to turn off the rear o2 sensors....go w/ the SCT Xcal 2 handheld tuner since ur going w/ a full exhaust...you can have it dyno tuned also...

but if u get cats then dont worry about turning off the o2 sensors

 

What state do you live in? The first set of o2 sensors are to keep your A/F Ratio correct...your car will run like poo without them. The second set of o2's are just for emission purposes to make sure your cat's are working properly. You don't need the second set and they don't affect how your car runs at all. Although I would recommend getting a tuner or MIL's to keep your engine light off.

As far as not needing cats....It just depends where you live and if you have emissions. If you don't have emission constraints then the only reason you'd probably get cats is to quiet the car down cause it probably will be really loud ....depending on what cat back you have.

What other mods do you have and are you planning on getting a tune after installing the long tube headers? Just with my mods in my sig my car severely was in need of a dyno tune because the A/F was way lean and not safe....your going to need a tune for sure with long tubes and don't get a canned tune you get when ordering a hand held tuner, put the car on a dyno. When my tuner loaded my canned predator tune and did a dyno run they shut it down mid way cause the A/F was so unsafe.

You might already know all that.....just trying to help a brotha out

 

and to ping in with my usual diatribe on the subject...

There's no reason to go catless. The miniscule amount of power they eat (high flow cats are pretty easy on the ponies) is nothing upside the real world good they do for the environment. As motor sports enthusiasts we are the people that will cause and receive the heat for "destroying the earth" by negating simple and effective pollution control devices like cats. EDIT: this is the case despite the realities of the matter being that most air pollution from hydrocarbon burning comes from electric power generation and then from normally maintained cars and like 30 generations down the line you finally come to the occasional catless hot-rod as a measurable source of added pollution.

Use at least 1 high flow cat on each side. You'll cost yourself maybe 3hp but you'll be doing your part to keep the air clean and the smog ****'s off our collective backs.

jjt and me are in the smog hell of California where long tubes are only a wonderful gitty dream and going without cats is just nuts being one of those things that local and state cops LOVE to look for and slap $1000 tickets at as fast as they can write them.

 

i live in kentucky, and am not sure about emission laws here, although many of the stangs do go catless. as far as my car, it is pretty well stock now. im looking to purchase the rest of my exhaust, c&l cold air, and bbk throttle body all to go on at same time when i get the car back out in the spring. but i dont know much about the tuning and how to control fuel/air ratio. (im just beginning at this)

 

take it to a dyno shop for the tune, let them do it. Not a time to start feeling your wheaties and do it yourself... at least not until you have a good base tune on it. Just tell em 12.5:1 on the AF.

C&L tends to lean you out pretty substantially so definitely get a tune immediately after putting that on... it's gunna cost a bit but the safety factor is worth it.

 

r3dn3ck it totally right about the dyno tune....you wouldn't believe how out of control my A/F was after just adding a CAI, catback and mid pipe.

gotMACH04....I'm not sure if you belong to the Mach 1 registry, but if you haven't already, visit the forum and you'll find anything you could possibly ever want to know about mach's and modding them. The reason I bring it up is because you mentioned putting a BBK throttle body on your car....do a search on the registry before purchasing it. I think you'll find it very interesting and will probably change your mind on doing that mod. I was going to get an Accufab TB for my car, but a lot of mach owners are having problems with them as well. I better mod would probably be a PHP Intake Spacer....it won't gain you a ton of peak hp, but you will see more hp through the powerband.

The below website is a review that Apex Motorsports did on the PHP intake spacer.....they aren't affiliated with PHP so it was an independent review. They have done some pretty cool reviews on catbacks and short throw shifters also....check it out
http://www.mach1review.com/PHPSpacerReview.html

Also, check out www.mach1registry.com I learned so much about my car by just doing topic searches and not even really posting.

 

Ok, so I understand the 'only 3 hp difference'
BUT do they sound all that much different than high flow cats? Honestly I think they would sound better and less annoying... but don't know fer sure.

 

do what sound different than high flow cats? off-road pipes do sound different than catted pipes. I think they're meatier sounding without all the popping and rasp.