: opinions on high flow cats

10-17-07, 09:02 PM
I have magnaflow mufflers on my 95 deville concours and I was wanting it to be a little louder. I was wanting some opinions on high flow cats, hollowing out the cat i have now, or just replacing it with a pipe. Some people have told me that high flow cats aren't much better than stock. Another thing, if I hollowed out my cat would it be safe to remove the resonator as well or what that not be enough back pressure. What kind of gains could I possible get out of this besides just being louder?

I live in Arkansas and they dont do inspections so I'm not worried about a fine.

10-17-07, 09:50 PM
Leave the cat as-is and remove the resonator. Louder, but you won't possibly set an emissions code, not for Arkansas, but for engine controls and dashboard lights.............no gains, just louder, which may sound like power.

10-19-07, 02:53 AM
would I still have enough back pressure if I hollowed the cat?

Highline Cady
10-19-07, 03:54 AM
95 Deville is a 4.9, correct? From my experience, I had a 92 Seville with a turbo muffler that I hollowed the cat on, and in my opinion it was the worst thing I ever did, besides the fact that the SES light came on which you can easily make go away with an O2 simulator, the engine developed a tick, long story short 6 months later the engine was done. It could have been coincidence but the car ran fine for years before this mod. In my opinion the 4.9 has to have some back pressure, not having it causes problems in the long run. The N*'s don't mind this mod besides throwing codes, once again easily solved by an 02 simulator, in my opinion. Some will say however that you'll lose some low end torque, I have time slips that prove otherwise. Or they will say that normal daily driving is when you notice this loss, personally I haven't noticed it. It is louder, no matter what you do it on, but in certain cases I believe not worth it at all, in my opinion.

Being someone who has done what your thinking of doing let me say, LEAVE IT ALONE. It's really not worth it. Besides that testing or not, if somehow you are found out, it is a felony if you're using the vehicle on the street. Chances of getting busted, slim, but besides that the 4.9s really just don't seem to like it either. Just trying to save you the pain I went through.

10-19-07, 04:30 AM
It's a 4.6, deville concours

10-19-07, 08:40 AM
As mentioned previously DON'T TOUCH THE CAT. You will cause yourself headaches. You're not going to gain anything anyway.

Highline Cady
10-19-07, 08:50 AM
It's a 4.6, deville concours

My bad, thought all 95 devilles were 4.9's, didn't think N*'s made an appearance in the devilles before 96. If you're gonna do it, you'd better order an O2 simulator right away, otherwise you'll be throwing codes. If your expecting any type of noticeable performance gain, it's not gonna happen. It will be significantly louder, however.

10-19-07, 09:12 AM
Specs for exhaust system back pressure readings
1996 to 00 Northstar Cadillac @ idle less than 1.25 psi and less than 3 psi @ 2000 rpm

2001 to 07 FWD Northstar Cadillacs less than 1.25 psi up to 2500 rpm's

I would put money on it that it should be 96 to 99 and 00 to current for the specs.

All 6.0L Escalades are .5 psi or less up to 2000 rpm.

Find a high flow cat that will beat that spec:histeric: