Heres some pics of my exhaust when it was factory versus custom.
Circled in red are the cats, blue is the x/h/y pipe area, and green is the muffler/s. the second pic they are technically resonators but same purpose.
The first pic is from the front of the car tawards the back.




4 cats, BEFORE the x/h/y pipe area.


Second pic is after my custom exhaust and is from the back of the car tawards the front. I had two cats removed and left the front cats, the ones that the o2 sensors are before and after.

 

Okay last post for a bit lol

 

you guys are awesome!
@baby gt. after your custom setup did you notice a huge difference in loudness with the two rear cats cut? im thinking about doing that now!
UNLESSS i should remove ALL 4 and replace them with 2 high performance?
what do you think? a waste of money and stick with the two stock?

 

I love the tone, I wish it was a tad louder, I think ditching all stock and having 2 high flow cats would have been perfect. My exact setup is stock manifolds, stock front cats, rear cats removed, h pipe, resonators, tips.

 

Alright cool! im all for the louder! So i should just buy two high flow cats, remove all the stock 4 cats? Another thing i already have brand new flowmaster 40s.... what do you think about that? keep em on?

Lastly, if i replace the 4 with new high flow cats, will i need to do something with the 02 sensors??

 

You put 2 high flows in front and stick MIL eliminators on the back so you dont get a CEL

 

Huh, I have yet to see one here with 4 cats. Factory or otherwise. The one I bought to start the build I'm doing now most definitely didn't, and it certainly LOOKED factory before I started.

Now see, where that second cat is on your picture, on the 3 mustangs I remember seeing here, is just a bung'd piece of bent pipe attached to the headers.

Edit: Also I know that another mustang I had was H-Pipe -> cats. My exhaust guy also did mine h-pipe -> cats, just looked under the car.


Edit2: That second set of cats up tight into the headers isn't visible from an inspection that doesn't involve a ramp, so you should be safe with 1 set of high-flow cats and ditching the other set. That should REALLY open her up.

As I mentioned, I'd also suggest headers. Opening up the exhaust port coming out of the engine a bit really makes it louder. If you do that along with everything else though you will see a MPG drop of ~2 but a nice horsepower gain when combined with a CAI.

 

They are visible from under the hood if your looking for them. Also I have never seen the cats after the h pipe, mind taking some pictures of your system from the manifolds back? Also the only headers worth getting are 94-98 take off headers (they came factory with headers) or long tubes, unless you have a whole lot done to the car you prolly won't notice a difference between those two though.

 

This hasn't been my experience. My shorty's perform just as well as my Long Tubes did and I don't have the issue where the long tubes where they were lowering the exhaust too much.

 

Not arguing that point, I mean your better off to spend the 50~ bucks in a scrapyard on single port stock headers than spend the 2-300~ on aftermarket shorty headers. They both perform the same. I'm not sure why ford downgraded to the manifolds they used on the new edge like they did.