I had a post in the general section about my Cat melt down…basically I was running redline in my 08 GT500 (Brenspeed package at 13 lbs boost) in 2nd gear when a cloud of chalk like material started blowing out the exhaust…I had sand like graduals in the pipes which were ceramic…as I and other MF members suspected…the cats were blowing out…I have removed them and they were probably only running 1/3-1/4 flow potential…the screens along with some sort of steel wool like gasket material was rolled up and collapsing inward upon themselves…I honestly cant see how the car ran as well as it did! I am going to install high flow cats with an H-pipe from MRT (Mustang Racing Technologies)…I am thinking one might want to pop underneath and pull the O2 sensors out of the cats and shine a light inside to see if there is a problem occurring…I have only 3400 miles on it.
I cant wait to see how much better it will run!

 

Geez....how did this failure occur in the first place?

 

My first thought is the stock cats are a POS!..but I did have a couple of misfiring spark plugs for awhile...could have allowed enough unburned fuel to pass to the cats and burn there...sending temps too high...

 

I need to get mine out and drive around a bit and see if I have any similar issues, but I drive nice nice. I am not mean to my 500.

 

Shella you are too funny! I was driving "nice nice" around town...probably why I fouled a couple of plugs! WOT from now on!!


"No more Mr. Nice Guy"...Alice Cooper

 

You mean, start rough housing our rides around???

 

Show us what you got!!!

 

YES YES YES!!!!!!

 

I have the new high flow cats with the H-pipe installed...can really see the difference in the tach moving through the redline...it was quite a bit slower before...now I have to be careful not to bounce it off the limiter at 6800 rpm...

 

Your Redline oil could be the problem. CI oils have a lower amount of ZDDP, because that is what clogs the cats. That's a big deal with flat tappet cams in older Windsor motors. Not a problem with the mod motors.

Some Redline oils conform to CI standards, and some are race only for use in cars without cats.