Dont remove them stay legal....gain power another way....Dave

PS..we are having a Tx rally oct 15-17 check events/happenings for infor.....

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1998 F-150, SC/Flairside, 4x2,4.6,auto,3.55s,nerf bars,cls 111 towing,bed liner w/mat,atlas polished wheels w/ 265 scorpions,all plastics guards/bug shields,air raid/k & n filter, superchipped, duals out the back corners, flow master 3 chamber, snug top lid, f-150 online sticker back window-honk if you see me!!! Fabtech 3 1/2 lift will be on by oct 11 (TODAY) I HOPE!!!

San Antonio

 

Note to all - Those things you guys are calling "resonators" close to the exhaust manifolds are actually "light-off catalysts". They are mounted close to the exhaust ports so that they heat up quickly for reduced emissions during the first few minutes after a cold start. Once the vehicle is warmed up, the main underbody catalyst takes over.

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1998 STX 4.2L V6 Auto
16.26 sec @ 84.43 mph

 

Just for info,
If your looking for slightly more performance, you should look into the Bassani catalytic Y-pipe. It provides for better flow with a less restrictive cat instead of 2. On the Mustangs they are popular modifications because Bassani's X-pipe has one cat per side instead of 3. With that pipe you keep the cat and it has O2 sensors in it with the plug to keep your computer happy. Just for info it is against Federal Law to remove a normally operating cat. But if it should need REPLACING then you can legally put on the new cat. Good luck,

Mark...

97 GT Mustang, 98 Expedition 5.4

 

I removed my cats and had a muffler shop put duals on. Pretty significant low end power increase and good acceleration in higher gears as well. This is an illegal mod and if you choose to do it, you will have a hard time finding a muffler shop to go along with it.(keep the o2 sensor in the set up and you wont have a ck.eng.light)

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92flareside 302-5speed
k&nfilter,march underdrive pulleys,flex-a-lite fan,dual exhaust-more to come!

 

You cant run a new Triton with out the cats. The O2 sensor is behind the cats, on the 5.4L at least, not sure about 4.6L. If you remove the cats, you will mess the air/fuel ratio up.

 

You cant run a new Triton with out the cats. The O2 sensor is behind the cats, on the 5.4L at least, not sure about 4.6L. If you remove the cats, you will mess the air/fuel ratio up.

 

I concur with nomad... I had dual exhaust put on my 96 351w f150 from the manifolds back. The o2 sensors are in the pipes where they should be and i have noticed a considerable increase in throttle response and a little increase in gas mileage. I had no cats on and no mufflers... i really enjoyed the sound, but i thought i would give a pair of flowmaster 40's a try and see how i liked that. I was very disappointed afterward; the exhaust was way too quiet AND i lost some of the throttle response again... so first thing monday i'm getting them taken off.

Does anyone have any experience with glass packs? I want my truck to sound beastly loud (preferably without the cackling of straight pipes) with a bassy rumble.

 

removed cats on my truck and running true dual 2.5" pipes into 4" tips. loud and mean you guys with single exhaust think your trucks are loud? i just laugh

 

for the most part i have to say everyone i hear sounds like the guys on the sidelines instead of the ones in the game. i have had alot of techno-bable like this before. usually from the guys with the slowest cars. on my mustang i put an offroad h-pipe on and as far as bang for the buck it was one of the best purchases. i think everyone keeps forgetting that an engine is an air pump. more air in and out= more power. if this was a cat back question everyone would say hell yeah. with that being said whats the difference. all the cat back systems do is provide less restriction. i am going to do it. but as far as why it is simply for mpgs. also you will need a mil eliminator do a search on ebay. as far as my mustang the CEL was on the whole time with no performance loss,same as on my IS300 w/o cats.

 

Yikes...2...4...6 ...?
On the modular motors (5.4), at least up until they went to 3V heads:
4 cats is the answer for the 2V 5.4.

I sitll think the 3V engines are the same, but I don't have one (my truck is a 97) so someone who owns one can chime in. At any rate...

2 pre-cats tucked up near the manifolds. These light-off a bit early for cold-start emissions. But aren't really needed once the engine is warm. I passed CA emissions without them, just make sure your truck doesn't cool down before you get tested. I gutted them so they are empty but it appears they are still there, since we have a visual inspection also.

Then 2 main cats after the first 02 sensors. These are the primary units.

You can run a mod motor without cats. But you'll either get a CEL of you'll have to turn the rear 02 sensors off with a custom tune. The two rear 02 sensors just tell the ECU if your cats are present and operating correctly.

The two 02 sensors closest to the engine give data to the ECU for correct fuel/air ratios. These are very important so don't muck around with them. But they don't care if you have cats or not, since they are pre-cat sensors.

I run a blower with duals, an x-pipe and two tiny Magnaflow racing mufflers (which are too loud for me). No pre-cats, but two Magnaflow high-flow main cats. Lots of other mods including complete fuel system mods & custom dyno tune from Danny Swanson, and like I said I even passed CA smog and they are smog ***** here.

 

I just recently had all of 4 of my cats removed and I didn't feel any noticeable power gains. Oh and when you remove them you do get a check engine light, but there's ways to fix that with a set of mil eliminators. But no power loss and no real gains either. Just twice as loud exhaust my truck has a power pack on it and now it sounds like straight pipes. Honestly just keep them on if there's nothing wrong with them.

 

Holy Old Post Revival!