I currently have a 3" single with ASM headers. I have all bolts on possible along with a 212/218 cam but will be going with a begger soon. I am considering going with a true dual exhuast with X pipe. I just know if doing this will be feasable

 

I wouldn't go with anything bigger than 2.5, but that's just my opinion. Whatever the size of the pipe is at your header collector is what size you want to run. Increasing (or decreasing) the size of the pipe will cause turbulance in the exhaust, causing the velocity of the exhaust gas to decrease, in turn, giving you pretty sh!tty performance. So if you do go duals, go with the same diameter as your header collector...

I want a sound clip when you get it done!

 

JMO, but I think you'll be happiest with your existing 3" single exhaust UNLESS you're really to go to a bigger (with more HP) engine. Duals look and sound really cool, but probably are overkill for engines of less than 400 HP. Again, just my opinion.

 

I agree. Stick with the single 3" until you go FI or start making some serious HP. That being said I just swapped to a true dual setup on the 4x4 even though it's N/A now. We had to build a new exuast system after removing the STS so figured why not makie it sound cool. We did a dual 2.5" with an X-pipe and 2 magnaflow bullets. Can't wait to hear how it sounds with 11:1 compression

 

I put true duals on with my 6.0 litre swap and Supercharger. It sounds mean! I also have not lost much low end. This was a necessity.

 

Go 2.5'' duals w/ your ASMs.

 

At what point would you "need" dual 3" as opposed to say 3" Y pipe into a single 4"??? Im thinking of staying with that kind of setup to give me some backpressure so I dont loose too much power down low around town and I could do dual 3" cutouts in my custom Y pipe. I really think this would be a sweet way to go for use centrifugal guys that are planning on putting some crazy power down. I dont think cutting two 3" bends and welding them to a 3" to 4" reducer would be as difficult to route or make as opposed to 3" with an X etc...

 

I am not sure of the exact math behind it. I just know that when I was building my Mustang for about 600rwhp the answer was always dual 3" exhaust. This was an FI setup.

I also see lots of 600rwhp+ LS1 guys running eaither dual 3" or at min. a single 4" Mufflex system.

With these kinds of details I feel that a dual 2.5" would be good for a basic FI truck or a top notch N/A combo to allow for some back pressure for daily driving and also because our exhaust systems are much longer than those of cars which adds restriction.

Maybe one of these chaust gurus could clear this up a bit for us.