Adding cats to my 2001 gt

[JustinMustang2001]

I have magnapacks on, and put on an o/r x a few years ago. I'm getting real tired of how loud the car is. I've decided to add cats to try and quiet down the car a bit and get rid of the smell, but am really not sure what to look for.
I've searched Amazon (I'm in Canada) and come up with 2 candidates I think would be good for my application:

Flowmaster 222 series 2220125
Magnaflow spun 53956

My question is, does a longer, larger diameter cat mean quieter? and what is the difference between spun and traditional cats? Will one give better performance than the other?
I'd like to quiet it down quite a bit.

Thanks guys,
Justin

 

[7991LXnSHO]

Knowing the year and engine for sure will help.
I know this does not exactly answer your question, but it might help anyway. How does this PYPES Cat X pipe cost compare to the two replacement cats and hassle? I do not remember my 91’s BBK cat y pipe being that expensive, and I am pleased with them. My car is a bit quieter, but it does not seem slower at all.

Pypes Mustang Catted X-Pipe Stainless Steel (96-98) GT XFM33

Increase performance and sound while staying emissions legal with this 1996-1998 Mustang catted x-pipe from Pypes!

lmr.com

 

[7991LXnSHO]

In the mean time, here are two cats that will make your car purr loudly. I’m not sure about the smell aspect.

 

[JustinMustang2001]

Its a 2001 gt with the 4.6l 2v.

Unfortunately I'm in Canada and with the exchange rate and shipping it becomes much more expensive than just adding a pair of cats. It would probably cost upward of 700+ CAD for a new midpipe vs around 250 for a pair of cats.

Very nice cats! Smell aspect is a deal breaker though...

 

[7991LXnSHO]

That answers one question! That’s cheap for two catalytic convertors. Cats started out as pellet filled, then honeycombs. If you were at my counter and “Stumped the Chump” (NPR Car Talk reference), about spun catalysts, I might call the tech line. I wonder if Magnaflow has info for us online.

In the mean time, how bad is the smell? Even without the convertors, to smell strongly like gas, I suspect a 2001 would have to be running rich.

 

[7991LXnSHO]

Ok, the catalyst looks like a ceramic honeycomb. It’s the body that’s spun instead of a welded clamshell. So no seams. Look under specs.

MagnaFlow Standard Grade Federal / EPA Compliant Universal Catalytic C

Keep the check engine light off with MagnaFlow Standard Grade Federal/EPA Compliant Universal Catalytic Converter 53956. The Universal design allows the part to fit a wide array of vehicles (cutting and welding required), and the stainless steel construction of this spun body catalytic converter...

www.magnaflow.com

As far as size and noise I do not know. It might be better to go with which fits best. it makes sense a bigger one might flow better, yet how the bigger case and more catalyst affects noise is just a guess.

 

[JustinMustang2001]

Running rich could be a possibility, although I have a tune from Bama so I would hope the a/f ratio would be set correctly.

I really can't seem to find any info on the clam style vs spun style. I think I might have to just take a guess on this one, leaning more towards the spun magnaflows because of their compact size. Thanks for your help!