I have a valid question if any body in the forum can prove this.
what is a high flow cat? what are you cfm ratings? all replacement convertors say high flow. what are the flow ratings vs stock convertors?

and as it goes for gutting the cat you will get a cel however there is a way around a 420 code use spark plug antifoulers.remove the rear o2 install antifoulers (some cars require 2-4) reinstall o2 inside the antifouler. what you are doing is lifting the o2 from the exhaust stream does not effect drivabilty and allows for a race use only cat or no cat at all.

 

I'll try to answer your question.

OEM cat from what I read up on flows approx. 250 CFM. Magnaflow is approx 325 CFM. But the thing is that not only are you replacing with hi flow development, the better thing is to replace with a larger flowing capacity. OEM is 2.5 inch from the manifolds down. The thing is it Y's together and then into the cat at 2.5 and choke the exhaust. The proper way to deal with this issue is to cut the Y off and have the 2.5 inch from eachsides of the motor meet in a replaced Y that converts to 3 inch.

Then installing a 3 inch converter as well as a 3 inch cat back system flows free unlike stock. AnOEM flow thru exhaust system flows about 250 max.This is because they are notset up to flow but rather, get the job done.When installing a true Cat and back system with Y conversion you can get about anaprox. of about 35 HP plus performance and fuel MPG's. Now I have seen claims of up to 480 CFM on the 5.9L although these are from very good sorses but no dynometer charts that I have seen.

Now I can vow to the claims. My truck woke up. But everyone is intitled to the own opinion.

 

well hydra I have to give this to you you are the first person to attempt to answer this question as I have asked this many times to the manufactures I distribute to and for. bigger is not always better when it comes to pipe. larger diameter pipe can have negative consequences. lower torque worse fuel economy. but you could achieve high end horsepower at higher rpm range usually at 3000 rpm and up. in all honesty for the stock d owner it will actually compromise performance gains using a 2.5 head pipe into a single 3. with 2.5 the surface area with 2 pipes would be 5 inch.with that surface area you would need amotor building over 450 hpfor that exhaust to be tuned properly.
I have been to many exhaust confrences, with magnaflow,flowmaster,xlerator,borla,red deer,goerlich,walker,dynomax,catco,jones,flo-pro, and aero turbine. and the question that i ask seem to turn the reps in a stir for explanations. I have a confrence coming up in febuary in which all the above mentioned will be there.and can't wait till i drop a bomb at flowmaster in which they don't reccomend x-pipes for use with thier mufflers rather they and i quote " usea h-pipeor ourd-port pipe with our mufflers" and they wouldn't explain why.but that isfordiscussion in adifferent thread. I design and manufacture custom pipes for a range of applications, and different manufactures for aftermarket performance companies. I wouldn't be surprised if a few forum memebers hereare running my design and manufactured pipe sold under a different name.

 

Nice to hear that someone knows this stuff. I'm vague, but tried.

Sounds like you are one that can answer your own question. I poured over hours of documents on this stuff just to try to answer this one. You are right about potential damage from little or no back pressure. This can lead to warping heads, burnt valves, and torque loss. Sure plain old horse power increase, with the following if your motor isn't built right to handle the exhaust.

I feel that a back pressure of 1 to 2 lbs. back pressure is good.

3 lbs. is getting too much in my opinion.

Just like headers. Well that is for another thread.

 

Hey guys I have question if i replace the cat with this one will it still pass smog here in California? i got the 420 code thats the reason im replacing it

http://www.partsamerica.com/ProductD...pe=145&PTSet=A

 

BUMP THIS!!

LMAO,I have posted in 2 other threads concerning the same thing but figured I would opt out of a 3rd.Good to see another guy in the field with "HANDS ON" experience posting up.

 

okay guys i changed the LDP and that made no difference. I went ahead and replaced the catalytic converter. The D still Stall alot. Seems to be backfiring and the D has no power at all. I will be replacing the PCM see if that the problem

 

Well a little update on this found out my Cat went out with in a couple days of installing it. The muffler shop said the D: is running to rich. this is the reason I had lost all power on my. its been a couple of days and my D: hasnt stalled so im happy about that