TieRod

Sense it's a 4500rpm engine dual 3's should be fine.

Whippled 496

iTrader: (4)

Yeah...thats kinda was I was thinking too.

Whippled 496

iTrader: (4)

Looking for some opinions as i get closer to the install and because I want to be able to make some decisions when I stop at the exhaust shop this Friday. I have decided to go with Magnaflow parts (muffler(s), X-pipe, and CAT's). I want a mild sound at idle and cruise and a nice "here I am sound" when I stomp it. My whole system will be 3" true duals all the way to the rear of the truck. I am thinking something in a 18"-22" muffler should do nicely. Only questions I have now are.........

1. Are two single inlet/oulet mufflers better than one dual inlet/outlet muffler? Is there a reason to go one way or the other?

2. If i were to go with a single muffler, should I go with an X-pipe seperate from the the muffler or go with the muffler with the X-pipe built in? Is there a reason to go one way or the other?

3. looking for part #'s of hi flowing Magnaflow mufflers (singles or duals). I am going with the ultra hi flow metalic spun CAT's (3" in/3" out), but have not decided on the muffler arrangement or part number just yet. I would like it to flow at least as well as the CAT's which flow close to 600cfm each.

Mangled03gmc

iTrader: (95)

I would go with two single 3 inch magnaflow bullets, buts thats me, plus i think it will sound better....

budhayes3

iTrader: (19)

I think dual mufflers will sound better also, plus the x-pipe should be as close to the headers as possible (if possible). If you have space constraints, then I'd go with the dual muffler with internal x, but if you can fit it, I'd do the separate x and dual mufflers.

Whippled 496

iTrader: (4)

Yeah, I want to get he X-pipe back as far as I can. How does the 2 single mufflers sound different than the 1 dual? I dont want it supper loud. Something like (2) 7" x 20" or (2) 6" x 22" mufflers? Whats the difference between the XL Turbo's and the standard mufflers?

hog

You want the X-pipe as far forward as possible. Its tuning effect is lost the furthur back it is. As exhaust temp is cooler and exhaust/sonic pulses have lost their energy.

Doesnt have to be an X-pipe either, a simple crossover pipe or H-pipe is sometimes easier to mount, and will still boltser low-mid rpm torque.


If you are using a dual 3" pipe, I would use a 2" crossover pipe.
The tube lengths of BOTH banks before the x or h pipe should be equal.
No sense IMO to run either crossover pipe, if it is placed behind the trans after the big 90º angle that brings the drivers side exhaust over to the passenger side.

You want the mufflers as far away from the headers as possible.

I wouldnt run a dual inlet/outlet muffler in this application. I would run dual mufflers with possibly some resonators before them. Running the per-mufflers(resonators) allows you to run large pipe diameters while still being able to keep the loudness under control.

I have run a dual in/out internal x (dual 2 1/2" in/out) and upper rpm power was stifled markedly when copared to a dual 2 1/2" pipe dual 2 1/2" catted turndown open exhaust. This is on a NA stock longblock Vortec 350.

I wonder what your stock dual 3" cats flow? I would be inclined to use those as their quality will be hard to beat as they are warrantied for 7-8 years as per EPA mandates.
It would be nice to measure the backpressure of your current combo.

peace
Hog

Whippled 496

iTrader: (4)

Thanks for the input HOG. I have a few questions about the following statements if you could elaborate please.

So you are saying to reduce the size of my pipe down to 2" before it goes into the x-pipe, and use a 2" x 2" x-pipe? Seems awful restrictive to cut an inch in size off the pipes before they go into the x-pipe unless I am not understanding what you mean.

Again, i dont quite follow here. With my setup, the header itself brings the driver side exhaust over to the passenger side before the tranny pan and right under the 4WD drive shaft. No big 90 degree bend after the transmission with these headers, the 90* is built into the header and it happens immediately after the dump down from the drivers side head. Have a look at these pics....







So you can see how having the same length pipe before the x-pipe in my situation would be near impossible.

Understood.

Do you have a recommendation on the best type to use?


I have been considering this as well, but I have no idea what they flow. I figured I couldnt go wrong by throwing on some CATs the are rated at 550cfm+. I also plan on putting in a CAM and heads later this summer/fall which will further increase flow out of the engine.

Lastly......what Magnaflows would you recommend (part #) that will flow well enough for my setup?

Thanks again for the help.

Thanks to "02 2500Avalanche" for some of these pics!

hog

Thanks for the pics, that really clarify things and really throws off my recommendations.

#1 A cross over pipe is an H-pipe. I mean to use a 2" pipe to connect both banks of your dual 3" exhaust. I would want each end of the H-pipe to be the same distance away from the collector of your headers on both banks of the dual exhaust..
with normal LT headers an H pipe will look like this

I-I

on your truck it may look like this
I
\
I


#2 OK, the header does that 1st big 90º for you. This will make bank to bank tuning very difficult. There is still a 90º bend to angle the exhaust back towards the rear of the truck.
On a more conventional header, the primary and collector lengths are pretty comparable bank to bank. In as much, running the exhaust from the drivers side bank over to the passenger side will result in a much longer headpipe to the cat than the passenger side will.

My whole point here, is to have EQUAL lengths of headpipes before each cat. In doing so you may have to stagger the cats appropriatly. Just like the Vortec 350's do stock.(if that helps you at all?)


In all honesty you probably wont miss an X-pipe or an H-pipe on your blown 496 truck. You arent going to be short on low-mid rpm torque with your setup no matter what you do.

Maybe run dual 3" exhaust into 2 mufflers with possibly some small glass packs before the main mufflers. OR run a nice 4"-5' single exhaust that will negate all of this H pipe/X pipe discussion.

I dont have any specific suggestions with part numbers.. I

To minimize catalytic flow loss, you can always run dual 3 1/2" cats with stepups before the cats and stepdowns after the cats. Just an idea.

peace
Hog

hog

These look like some nice mufflers.
http://www.magnaflow.com/02product/02race.asp

peace
Hog