i totally agree!!!!!!! cochran is clueless

 

Why do you have 1.75" piping? I thought 2.25" is the smallest they put after the muffler? I don't think a 2.25" tailpipe will hurt much provided there's a free flowing muffler, but 1.75" is way too small for single exhaust, 2.5" would go a lot better. The 2" duals on my Suburban are way too small so I can see how a smaller single pipe would choke it. The Vortec 350 needs at least 2.25" duals but i'm going 2.5" true duals since i'm putting on headers and getting an x-pipe put in, and that'll be good size after I get the PCM tune done. So when that's put in if anyone with a fullsize 4.3 wants so stainless duals, i'll sell them cheap lol.

 

i dunno what exact size the piping is all i know is its 2.5 going into the muffler and a crap ton smaller coming out. so either way its going to be: manifolds factory y-pipe(or collector dont care what u call it) 2.5 inch piping and then NOTHING! no tail pipe.

 

Well my experience with a friends truck we had to run open headers for a day and it ran fine before, ran like **** open and ran fine again with an exhaust. So in my experience the backpressure was needed. So before you say I have no clue might wanna find out my story. If it works good for others fine. Have fun with the noise complaints if you live in city limits.

 

well. if he ran open headers he eliminated the rear o2 sensor which is why the truck ran like ****.

 

Well if he ran open manifolds those manifolds aren't the tubular style and those are made for stock motors with a full exhaust with piping and o2 sensors. No body is talking about running open headers we are saying that backpressure is a myth. Its not what a motor wants or needs by any means. Backpressure is a restriction from the exhaust gases being pushed out of the motor. The only reason we even have mufflers and cats is to comply with sound ordinance and legal emissions. In reality your truck/car would run the most efficient with straight pipes with the proper size piping. It cant be too larger to so it becomes dead gas and it cant be too small so it doesn't fully scavenge all the exhaust.
That too

 

The post cat O2 sensors don't control the air/fuel mix, they'll just trip the CEL if they sense no cat or a clogged cat. It's the first O2 sensor you need for the engine to run correctly.

 

and a CEL means the truck is running on a base tune, IE, extremely rich.

 

That really depends on what the code is. Besides, base tune can hardly be described as 'extremely' anything. It is inefficient, yes, but...

Also, just because someone has their terms mixed up, it doesn't give people the right to berate him. If that is how some of you choose to contribute, there are other forums where that kind of childish garbage is perfectly acceptable, but it is not acceptable here.

We had the whole backpressure vs. scavenging in another exhaust thread.

 

I really like the rumble from my flowmaster super 44 with no cat. Had the original 40 on it as well, and its alot more raspy and not quite as deep.

And i cant say ive heard a magnaflow on these ive liked yet.