Ok, lately my truck cant seem to get out of it's own way... I thought that the injectors might be getting clogged so I cleaned them with the in tank additives. this helped out alot, but I still think there is a problem. I'm susupecting the fuel pump is loosing it's volume at high demand. But anyways... the point of this post is that I also thought the cat was rattling so I took it to the muffler shop that installed it and had them look at it. they did a flow test on it and gave it the thumbs up. what they did notice however was the mid pipe between the 3" cat output to the 3" flowmaster input was only 2.5" and recommended that I swap it out. So i told them to go for it.

Damn, what a difference! truck runs awesome now, and it still has a problem (possible fuel pump).

So the point of this post is to make sure that when you do a new cat/exhaust, dont leave any exaust plumbing that is not the right size in there.

my setup = gibson headers to stock y-pipe to a carsound cat 3" output (not sure what the input is, probably 3") 3" from the cat to the flowmaster (also 3"). This summer I HAVE to change the 2 precats, at that time, i'm going to have them make a custom y-pipe to eliminate the restrictive bends in the stocker.

 

I have wondered this myself often. Glad to see that it made a difference. I have been afraid that it would open things up too much. I also wonder about increasing the diameter of the stock y-pipe for the same reason. What was the cost just for that small peice of pipe, installed?

 

60 bux. I would not change the size of the y-pipe, I would just make it a mandrel bent y-pipe.

 

3"? i think my cat and down pipes are 2.25... the same size as the rest of the stock exhaust piping....i wonder why yours is bigger then mine

 

it's the output of the cat that's 3" My y-pipe should be just like yours except for the cats, I think it's 2.25"

when I first got my truck, I didnt notice the dual cats and was bitching to myself for getting it, however, after modding the hell out of it the dual cat setup is now a good one... reason being that when I leave this f'd up state, I can go with a true dual setup and i'll have the o2's already wired up to the pcm... (that is of course if I dont upgrade to a diesel...)

actually, after reading my post.... the 3" makes sense now... the dual outs were reduced to 2.25" which was close to a single 3" exhaust setup... that's why the torque is so good... damn, why didnt I notice that before??? [:@]

 

wait...explain that again? you lost me

 

you leavin cali? lol when you coming to ny?

 

the performance cat is 3"in/out... if you kneck it down after the output, then open it back up, it's like trying to shove something though a small hole. have all the holes the same until the end and it'll flow really well.

so what i'm saying is if the cat is 2.5"in/out, it's ok to have the pipe between the cat & muffler to be 2.5" if it's 3", match it up. this is where we went wrong on my truck. I was expecting it to be the same size and I never really checked after the install.

 

long term (4 year) plan is to leave CA for the North... WA or OR... havent decided yet. the wife is going back to school to become a radiology tech in August so we're waiting until she's out and my son is outa high school before moving anywhere.

In the nearby town of stockton, they have begun pulling over the "illegally" modded rice rockets. one more reason to get outa here. It's gonna suck driving the M3 now... you can hear me blocks away!

 

i couldent handle living in a place where they have noutheing better to do than tell you what you can and cant do hee in canada they have some resterictions but there pritty leanient and there arnt neatley as many as you guys talk about