'03 Mounty V8 -- exhaust questions

[Von Kaiser]

I just bought my '03 Mounty back in February and the wife is going to let me do some minor mods short of getting a supercharger (that is, not yet). I'm the second owner. It's the Luxury trim model with literally every option checked except AWD. Got the owner's manual case with the original monroney sticker. The first owner ordered it with the Class III/IV towing package with the 3.73 gears among other awesome options that I'm benefiting from for the low price of $6,800.

The first thing I did was take that crummy paper air filter out of my air box and put in the K&N drop-in. Had great luck with these in my past Fords and have already seen a slight MPG (1.5~1.8) and acceleration (0.2s~0.3s to 60) increase.

Next on my list is a good muffler (and exhaust tip). I've decided on the Borla XS muffler due to having the best bang for your buck according to the charts posted on this very forum. But, I'm not sure what size piping came with my Mounty from the factory. Is it 2.5" or 2.25"? I haven't been under the car since I bought it, and I wasn't exactly looking at exhaust piping size. I love the way Modular's sound, and I absolutely love how my Mounty sounds with the slighly beefier growl when at WOT with that intake change. I've literally got compliments from people (including Mustang owners) on how good it sounds. The cost for the Borla XS with 2.25", 2.5", and 3.0" is the same so I'm wanting to get the right size.

Also, I understand that this thing has (retardedly!) 3 catalytic converters. Left, Right, and a Rear. Can I get the rear one cut off (legality notwithstanding) and still pass emissions? The O2 is before that rear cat right? Does this also mean the car has factory dual exhaust Y-piped into 1 exhaust pipe where that rear cat is located before exiting the back of the vehicle?

This is my first truck so you'll forgive me if I'm not very knowledgeable about it at the moment other than the basics. I come from sports cars and sport compacts (aka hot hatches).

Any help is appreciated.

 

[JoshMcMadMac]

A muffler will make little to no difference in performance. If that is the ultimate goal, go with a cat-back exhaust. Magnaflow makes a nice one that can be had relatively cheap and is stainless. If you are going for a specific sound with the Borla, I believe the factory exhaust is 2¼" there.

It is a y-pipe setup. The removal of the third catalytic will not impact your ability to pass an emissions test provided the others are in good condition. You would not pass a visual examination, though.

 

[Von Kaiser]

A muffler will make little to no difference in performance. If that is the ultimate goal, go with a cat-back exhaust.

What do you consider "little to no difference" in actual numbers? 3hp, 6hp, 8hp at the crank? To me spending a couple of Benjamins for the added sound and a few extra horsies at the crank is worth it. My first goal is noise here, and so any extra horsepowers I gain at the crank is like extra credit for me. When the money is not really an object a better exhaust system manifold back will be considered.

I believe the factory exhaust is 2¼" there.

Awesome thank you, this is exactly what I needed.

It is a y-pipe setup. The removal of the third catalytic will not impact your ability to pass an emissions test provided the others are in good condition. You would not pass a visual examination, though.

Is it conceivable for me to not use the Y-pipe and just have 2 2.5" pipes instead? I don't have AWD so I've got a little extra room don't I?

Thankfully I've got members of my 3rd gen Fbody club with connections to state inspectors that really don't care about anything visual. Just as long as the vehicle doesn't throw any codes and or fails the sniffer test it's all good.

P.S. I saw you've got under drive pulleys and a tune, what kind of gains did you get from these? Got any videos of what your ride sounds like?

 

[MO-Explorer]

The way the fuel tank sits make true duals hard to accomplish unless you bend the right side over to the left and then straight back. Also the independent rear suspension has very little room for a larger diameter piping.

Speaking from experience just replacing the muffler doesn't give much if any performance gains. It has also only given me approximately .5 MPG's increase.

 

[Von Kaiser]

The way the fuel tank sits make true duals hard to accomplish unless you bend the right side over to the left and then straight back. Also the independent rear suspension has very little room for a larger diameter piping.

Speaking from experience just replacing the muffler doesn't give much if any performance gains. It has also only given me approximately .5 MPG's increase.

So keep the stock piping through the y-pipe, cut the 3rd cat off and put my muffler choice on and just enjoy the sound improvement?

 

[MO-Explorer]

I will not support that since it is technically illegal in some states. But yes that's an option.

I love the sound of mine with the third cat still intact. Its not the Borla but I love it anyways. It's not as much of a muscle car rumble as it is an Exotic styled v8 sound.

 

[Von Kaiser]

I love the sound of mine with the third cat still intact. Its not the Borla but I love it anyways. It's not as much of a muscle car rumble as it is an Exotic styled v8 sound.

Got a video or audio clip of yours? Also, what exhaust did you get?

 

[MO-Explorer]

Cherry Bomb Vortex Muffler

Clip:

I need to get another vid since it's warmer now, and they had a leak on the weld that I got fixed

Edit (copied wrong link)

 

[Black Dynomite]

..... Is it 2.5" or 2.25?....

Josh is right, it should be 2.25, however if its anything like mine, it is only 2.25 from the 3rd cat back. If you want to ditch the cat, you may find it is 2.5 before the cat.
I ditched that cat and run 2.5 all the way from the Y.

 

[Von Kaiser]

I ditched that cat and run 2.5 all the way from the Y.

This is good news. Means more out flow if I stick with the same size piping instead of choking it down to a smaller pipe. Is this a correct assumption?

Also, do you know if there is an undercarriage picture of something close to my vehicle year so I can check out how the exhaust is ran?

 

[MO-Explorer]

Here is a diagram showing how it runs, I will try to get a picture tomorrow unless someone beats me to it.

 

[Von Kaiser]

Thank you, you've been most helpful.

 

[MO-Explorer]

My pleasure, glad I could help. I've been the student for a while on here, just passing along some knowledge. I hope you continue to love your Mounty!

Sent from my iPhone using Forum Runner

 

[Von Kaiser]

My pleasure, glad I could help. I've been the student for a while on here, just passing along some knowledge. I hope you continue to love your Mounty!

Thanks for that.

I enjoy my Mounty quite a lot thanks to it's 3.73 gears. That and it's quiet and comfy.

Now if I can make it almost sound like a Mustang GT, get a little over 300 hp, and get my 0-60 time to around 7.0 seconds flat or less at some point I'd be even more thrilled.

 

[JoshMcMadMac]

Now if I can make it almost sound like a Mustang GT, get a little over 300 hp, and get my 0-60 time to around 7.0 seconds flat or less at some point I'd be even more thrilled.

The sound you can get close...I would still recommend looking into the catback for the best chance at that. The 300HP mark is a bit farther off, though. You can get a decent amount of power out of bolt-ons, but I would not count on seeing anywhere near a 25% increase from them. 20-30WHP total for all of the mods listed in my signature I would guess; let's just call it a 10% increase.

 

[Von Kaiser]

The sound you can get close...I would still recommend looking into the catback for the best chance at that. The 300HP mark is a bit farther off, though. You can get a decent amount of power out of bolt-ons, but I would not count on seeing anywhere near a 25% increase from them. 20-30WHP total for all of the mods listed in my signature I would guess; let's just call it a 10% increase.

Since I'm starting at 239hp at the crank the best I could hope for on minor bolt ons is the new edge Mustang GT's 260hp at the crank if we assume 10% increase? I could live with that.