Duramax Dual Exhaust

bigdogs · November 27, 2003

I've looked at some of the replacement HP exhaust systems for the duramax and they all seem to be single exhaust. Why is that? Why don't they run true dual pipes (assuming there is no cats like on mine)? This is my first diesel so maybe it is a no no on them??

Thanks

Colorado Kid · December 2, 2003

Mostly it's because all the exhaust goes through ONE turbocharger.

Roofer · December 2, 2003

It's fine to run duals, but most don't. A single outlet system is expensive enough with the big pipes(4"). If you want duals, I would get dual 4" pipe ran the whole way from where it starts at 5". I have a chrome 5" tip on mine, but it is hard to keep clean with the diesel smut coming out of it. Also, stainless is spendy but worth it. On mine, I just had the muffler removed and a straight pipe installed along with the 5" tip. It is a bit loud, but not bad in the cab.

Machine · December 2, 2003

4" duals do look great, but it costs more money. The folks at Diesel Performance Parts.COM are introducing a 4" dual system with 5" tips for about $799. Their single 4" exhaust with a 5" tip goes for about $490. An extra $300 for looks rather than performance - no thanks, the single system looks tough enough. Besides, dual exhaust running out the arse of the truck makes it look like a GASSER LOL

BlackSilver · December 3, 2003

Besides, dual exhaust running out the arse of the truck makes it look like a GASSER

Yup, there goes your resale value into the tank!

got dirt · December 3, 2003

Gibson Exhaust makes a dual systemand also ATS turbo systems

SoMnDMAX · December 3, 2003

I always ask myself self- "Why??" when this question comes up.

To each their own I guess. From an efficiency stand point you'd be hard pressed to convince me the duals out perform the single. In all actuality, the duals will under perform in most cases, and actually "plug up" the engine so to speak. JMHO.

Roofer · December 3, 2003

I'm not sure what you mean by "plugging it up"? I would think it would breathe better, but I'm no diesel mechanic.

I can see though, that maybe a single 4" would be plenty.

Forum member "Broker" runs duals on his Duramaxes. This is what I read anyways.

I had straight pipe duals on my 5.3 gasser and did run into trouble with not enough back pressure. I would think this wouldn't happen with a diesel.

Machine · December 3, 2003

Seeing that the Duramax aftermarket exhaust starts at the downpipe - A single 4" system would be the easiest way to get from A to B... I assume. In addition, the fewer bends in the pipe offer the less restriction for a turbo diesel.

bigdogs · December 3, 2003

Where is the turbo mounted in the exhaust stream? Is putting a dual pipe setup on a Duramax diesel next to impossible?

Also what size is the OEM pipes on it? It looked pretty large to me

Machine · December 3, 2003

I don't know if it's impossible, but I don't know how a true dual exhaust would be fabricated. The downpipe is a single pipe that runs from the turbo into the exhaust system... The dual exhaust that most of the diesel guys offer are usually single in / dual out at or after the muffler.

The stock exhaust is 3.5" with a pretty restrictive muffler. A less restrictive, 4" single exhaust with a straight through muffler can lowers egt's by 150-200 degrees.

Red2500HD · December 4, 2003

I guess you could put a 2nd turbo on and run "true" duals all the way. Now THAT could give you some SERIOUS boost. My brother-in-law did that with a pre-turbo Ford diesel. Man, did that change things. Made it almost as good as a Chevy'