Swedenrockers

Hi guys,
I have an C5 that need replacement of one of the cats.
Im thinking of replacing the both of them and on my searching on the internet I saw Magnaflows '59955':
http://www.magnaflow.com/02catalytic...niversal=59955

Is there anyone of you here that have experience with these or know
the pros and cons of using those?

My pros of these are, Stainless steel - no rust, metallic monolit - rougher than ceramic, the in/outlet is 2 1/4 - it will fit against my Milltek cat back.

My car is all original (I will fit the Milltek system at the same time as the new cats), and I have no intention of gaining more hp´s or anything like that, I just need new cats cause one of them is totally empty and the original exhaust is totally rusted.

GTA_Driver

No experience but nice to have cats that function. High flow cats and cat back exhaust will provides slight boost in HP.

Swedenrockers

Yes. Its also an must to pass the yearly test of the car (I dont know what the name is for that in the states.
The long story of this is that the tranny broke down earlier and while removing the exhaust it also broke to pieces because of the rust and one of the cats where empty. I found most of the subtrat 'inside' the rear bumper.

I can add another question also if anyone has the answer, are cats (generally) with higher flow, harder to heat up than regular (standard) cats? So they will have a longer heat up time before they start to work?

SloopJohnB@mac.com

General rule for turbos is that every psi drop in back pressure gives about 4psi increase in boost…but 2.7T is boost controlled, so it really doesn't matter. You might get a faster spool up and as GTA said, slight increase in hp.

Swedenrockers

Thanks for your reply, but I have an 4.2, so its naturally aspirated as you surely know.
But non the less the HP is not of an interest, what I want to know more about is however there is a long warmup time before the cats are effective and if the Magnaflows are suitable for my car?

SloopJohnB@mac.com

Sorry, missed that it was a 4.2

Swedenrockers

Yes, I understood that.
However, maybe you have any ideas to my question anyway?
The question are many, but the answers are few.
If I change the question to:
Those out there who have changed their cats, what cats did you use instead?