So I had two highflow magnaflow cats (part number 94106) and I'm pretty disappointed. I already had a si/do flowmaster 40 and i just added the two cats in place of the rear two cats and left the front two pre-cats.

why do i not really hear any difference at all? shouldnt it be much deeper and louder?

thanks.

 

Cats aren't for sound lol and all you have to do is remove the rears, your forward two cats are more less high flows. But you can't have any leaks in the Y or you'll get a CEL, your right at the edge of your programed efficiency parameters, so it has to be tight. High flows are mainly used in conjunction with headers. Stock rear cats are to long.

IMO the stock forward cats are better positioned for flow and velocity if your running stock manifolds.

Why are some of you calling these "pre-cats" ? We don't run resonators stock right,(?) - correct me if I'm wrong, but we run 4 full blown staged converters. Ford left room for improvement in our exhaust systems. You have to know how it works, specially if you want USABLE torque and power. If all you care about is sound, just hack it up lol.

 

No cats aren't for sound BUT higher flow should amplify the mufflers output...thus resulting in more sound. I don't have an answer for ya bambo---DirtySCREW

 

the only time people have found increased noise after adding high flow cats is when they delete all 4 factory cats...



remove the fronts and you'll notice a huge change

 

x2.

 

they are actually called pre cats. the front 2 are designed to quickly burn of the majority of left over gas before it gets to the second cat so that the second cat can do a better job at converting the harmful gasses. so there for they are called pre cats. they are the reason some of our trucks, mine included, have a slight tick that sounds like a lifter. most notable in gear stopped and idling. it was very annoying, but its the design, so couldnt really do much about it, except get headers (which i did later, lol.)

if you want sound improvements, yes, remove the pre cats and you will get it. but if you really want some sound, buy some headers. lol. thats what i did. went from stock exhuast to magnaflow si/so 3 inch. it went from plane to having a decent town, but not overly loud. then i put on a dynatech long tube header system with down pipes and the magnaflow cats included and designed to hook up to the factory exhaust at the pipe split but of coarse i put it to my magnaflow si/so. then it went from having a good tone to sounding like a freakin race car. i love the sound of it. its amazing. the down fall, the system cost me $2000. the plus side, it will last the life of the truck cuz its stainless and it sounds amazing and added a good amount of by the seat of the pants feel to the power.

 

So "pre -cats" is made up? Your guys slang? Crap, I'll find out in a minute lol.

 

I googled "Ford pre-cats" and got Darren's video's lol and a bunch of Toyota data. Iduno.

My truck sounded the best when I was running my forwards (pre-cats) and a Flowmaster 50 race series (not the SUV series). Sounded like an old GT Stang. It was slow as hell tho. So you can get that $2000 sound making a few cuts and splicing in a staight pipe, been there done that. You won't get the performance, durability and longevity that the Dynatech's offer tho, their one of the best ,-if not THE best IMO. The only LT's I don't like period is OBX, - They chumped us, their the shortest LT header I've ever seen and create way to much cab noise. They look nice, I'll give them that. Pace Setters are the longest and perform, but yea, their metal and a PITA fudging in a converter on the 4x4's. I had to cut the High Flow flanges and weld in a slip fit to adapt to the Pacesetter collectors, - it's that tight on the 4x4's!! That was fun ( :

 

I call them pre-cats cause thats what i've seen on here. My bud that worked in an exhaust shop refered to them as pre-converters too. Go to a ford dealer & they would be I.D'd as front converters.

 

Yea, I had to laugh when your vids popped up lol. I just haven't heard that before, figured I was out of the loop or something. ? Maybe I am ?

 

my guess is i should have just added another muffler in there to make it a true dual system and left the cats alone.

i guess ya live and learn, i dont know where i got the cat=sound equation from... ill just blame in on the FAU math department.

 

Wait , yea like others posted ,- remove your forward cat's. Your alright, I missed that one :o - High Flows are meant to run solo. Your not hurting anything with your currant set up, but as far as sound, you have twice the amount of sound deadening than needed. Their not for sound, but ARE sound deadening..

You don't have to remove tho. -The cheapest and quickest thing to do for you at this point is drop the front of your exhaust system down and GUT your forwards (pre-cats).

I think Patrick (Patman) has a how to on that. I've done it with a long auger bit and a shop vac.

You'll get twice the sound, It won't hurt anything and will cost you nothing.

 

what about a CEL? is this something that I can do myself if the rest of the exhaust has been welded?

ill pm that guy and see whats up, thank you so much!

 

haha i call them pre cats to

ive gutted some stopped up converters on a windstar in one of my college classes that was fun

 

Yes , you can do yourself.

You have a 3 valve, so your better off asking Darren about the CEL, you SHOULD be okay running the Magnaflows. I'm not that familiar with the 3v programing.