'99 Victoria bad cats... gut or hi-flow?glasspacked or flowmaster?

[p71nmd]

Okay i have a '99 Ford Crown Victoria P71 with the 4.6 , an engine code came up with a bad cat. I have a couple of questions okay being dual exhaust on each side theres a catalytic converter coming down at an angle after that it straightens out theres another catalytic converter looking thing but has no O2s on it or after it. On this year is there 4 cats? and i heard on these type of cats they cant even be gutted is that true?? And lets say if they are gutted what is this tuning every1 is talking about? How do i tune it if i gut them and do i have to tune? I can buy the 02 simulators but i dont know how to tune it. So whats better gut them if i can and use the simulators and "tune" it or buy high flow cats? Also i like the cherry bombs and thrush glass packs and the price is better than flowmaster! Any1 have any sound clips of a glasspack exhaust on a 4.6 motor?? Well any help is appreciated since i wanna take of this problem!!!

Thank You!
Jay

[murphmobile2]

I would prolly just replace the cats... some cars run funky without 'em, especially the newer cars.

The ones without o2 sensors are more than likely just resonators, those can be cut off. If you want more sound... those can go.

And as for glasspacks or flows... Flowmasters will make it sound like a Mustang... until they see a CV coming down the road, lol. Don't know if that's something you'd like or not? Glasspacks... they'll just give it a slightly blappy grumble. I'd get some tips, maybe 2.5" outlet tips, if you get glasspacks. Gives them a MUCH nicer tone.

Flowmaster = throaty.

Glasspack = raspy.

[p71towny]

I doubt your cats are bad on a 99 unless it had some other issues, but if you want to gut em its no biggie. You can get by with the O2 simulators, they go where the rear O2s were at. It will sound better gutted. I love my flowmasters and gutted cats. As I understand it glasspacks don't sound too bad on 4.6s.

[88Vic]

I'm not sure if gutting the main cats and get O2 eliminators requires a tune, but if you do that along with ugrading the entire exhaust and other mods like a Marauder airbox, then a tune is required. I think you can go with a Marauder exhaust, which is 2.25", and gut the cats and go with glasspacks with Marauder tips, that will definetly get you noticed. That along with a Marauder airbox and tune and you should be moving pretty good too.

[1987cp]

Mufflers are pretty much a matter of preference and how much you want to spend. Flowmaster products are high-quality and several sound levels are available, but glasspacks or cheaper turbo-style mufflers can be great too. I'd suggest requesting catalogs from Flowmaster and Walker/Dynomax - they're free, and they're great references. As I recall, both Flowmaster and Dynomax have sound clips linked from their websites, and there are oodles of Mustang clips available with a few Google searches.

Since high-flow cats seem to perform just as well as no cats, the only reasons to eliminate them are cost, sound, or if you plan some sort of abuse that might shorten their life expectancy.

[p71nmd]

Thanks for the input every1! very helpful

[87vicFIVEO]

Find the cause of the bad converter first, if the engine is running properly and the converter itself hasn't been damaged (impacted) they should last longer than 8 years.
What OBD II code did your pcm set?
Where there any other codes?
Try and get under your car and tap your cats with a pry bar and if you here material rattling around the honeycomb material inside the cat may be broken.
If raw fuel is exiting your engine (due to a rich condition) it's burning off in the catalyst element....wich can eventually cause failure.

[Datdambear]

I have gutted my cats...MIL eliminater needed...No other issues...2003 Crown Vic LX Sport

[97marquismuscle]

I actually am a certified technician on these sort of things... and basically alls i can say is when putting on my duals i didnt bother removing the cats.. it doesnt make it any louder anyways and doesnt add or take away any sort of horsepower. My car runs big straights and it sounds like a dragster and still is street legal. (somewhat ) but gutting it wont do anything but give you problems most likely.

anyways if you have anyother questions let me know.

[1987cp]

I actually am a certified technician on these sort of things... and basically alls i can say is when putting on my duals i didnt bother removing the cats.. it doesnt make it any louder anyways and doesnt add or take away any sort of horsepower. My car runs big straights and it sounds like a dragster and still is street legal. (somewhat ) but gutting it wont do anything but give you problems most likely.

anyways if you have anyother questions let me know.

Cool, always good to hear from someone with more actual knowledge than most. And another member near Lansing, too! I think this calls for a celebration!

[Datdambear]

I actually am a certified technician on these sort of things... and basically alls i can say is when putting on my duals i didnt bother removing the cats.. it doesnt make it any louder anyways and doesnt add or take away any sort of horsepower. My car runs big straights and it sounds like a dragster and still is street legal. (somewhat ) but gutting it wont do anything but give you problems most likely.

anyways if you have anyother questions let me know.

Well I am a ASE cert and have some ford and AC delco training under my belt.And in some cases the removal of cats along with hipo tuning...MIL eliminaters will enhance performance....There are some people who say there was no differance there are some that say there is...Once you do the cats and put MIL eliminators in it will put the ecm back to thinking they are there and will stop the issues of fuel consumption issues...So Yes remove the restiction...free up the flow let it breath...

[97marquismuscle]

Yeah but would you put the money in or the time for the VERY little gain of power? Seeing how for about the same time and money and legal way of doing things you can just slap on a 75 mm throttle body and gain so much more? All in the person flipping the bill i guess.. but just me i wouldnt bother messing with the cats but a very reasonable response..

and mainly no cats... not legal.. i wouldnt suggest doing that to your car..

[87vicFIVEO]

I actually am a certified technician on these sort of things... and basically alls i can say is when putting on my duals i didnt bother removing the cats.. it doesnt make it any louder anyways and doesnt add or take away any sort of horsepower. My car runs big straights and it sounds like a dragster and still is street legal. (somewhat ) but gutting it wont do anything but give you problems most likely.

anyways if you have anyother questions let me know.

.....not so sure I agree with you there. Removing cats on certain vehicles (like ours!) can definitely make the exhaust louder. The more modifications you make to a vehicle the more noticeable the restriction caused by the cats becomes. Cut open a cat and you will find a honeycomb material that the exhaust must flow through...this chokes the motor somewhat. I too am an ASE certified tech at an independent shop.

[murphmobile2]

.....not so sure I agree with you there. Removing cats on certain vehicles (like ours!) can definitely make the exhaust louder. The more modifications you make to a vehicle the more noticeable the restriction caused by the cats becomes. Cut open a cat and you will find a honeycomb material that the exhaust must flow through...this chokes the motor somewhat. I too am an ASE certified tech at an independent shop.

Yea, there is a VERY noticable difference with cats removed.

Definately gives a good increase in decibels, lol.

I aint no mechanic, but I know my exhaust.

[1987cp]

I don't suppose some of the increase in performance from removing the factory catalytic converters comes from the tendency to use freer-flowing pipe than ran through that region originally?