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Best exhaust system for low end torque and power.

58K views 17 replies 7 participants last post by  03Rammer 
#1 ·
Hey guys what's up. I have some questions concerning exhaust systems for power.
What is the best exhaust system for low end torque. Not high end power or peak hp or the like. I mean low end torque for hauling, throttle response, etc. I know there is alot of other upgrades like cams, power chips, gears and the like but this is for exhaust only.

-Stock from exhaust from cylinder heads to tail pipe.
-Aftermarket headers with stock catback.
-Single catback exhaust with stock headers.
-Headers with single catback.
-Headers with dual catbacks.
-Or true dual exhaust. From head to tail. Independent on both sides. No "Y" pipe.

Out of these 6 exhaust systems. Which one will net more low end power??
I don't think anybody has true dual exhaust as this would be a custom exhaust. But does it have an advantage over the other ones even if its for a few LBS of TQ??

What about dual catbacks vs single catback. with headers of course.
I keep reading mixed things about these to. Some say that the single is more for low end torque but I also read that the duals are better than the single for low end torque because of the smaller diameter pipe with increases velocity of the gases. :thk:
So whats what?:4-dontknow:

Thanks guys.
 
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#2 ·
Don't expect any huge gains with just changing the exhaust! The biggest restriction with exhaust is the size of the exhaust valve, you could spend some time porting the exhaust though to help reduce terbulence in the port. In order to really take full advantage of the exhaust you are going to want to match it with a cam and really with a certain amount of lift. Certainly going from those stock manifolds to headers will help with scavenging but the gains again aren't going to be as significant as they are usually advertised.

As for a catback, not recommended if you live in a emissions control state. Cat-Back isn't as efficient as placing the cat closer to the engine, however if you live in a state that doesn't have emissions laws then hell catback it is. Another thing you're going to have to consider is the position of the O2 sensors as the pre cat o2 is for the fuel mix and the post o2 is for the emissions, thats with vehicles 1996 and newer magnums as far as I know.
 
#3 ·
The stock exhaust is very good. The restrictive parts are the manifolds, y pipe, and muffler. If you put on shorty headers (which are available for your truck I believe) and a straight through muffler (like magnaflow or dynomax) you'll see great gains at low and high rpm. Replacing the y pipe would be another benefit but it makes more of a difference at high rpm, not low rpm.
 
#4 ·
Oh good. Now I am fully aware that I won't obtain big gains. A few lbs of tq that could or could not be noticeable but every little thing counts.
Here in Nebraske we don't have emissions, so its ok.
Now from duals to sngle pipe. Which one will net more torque? Even if its one tq lbs of difference.

Thanks.
 
#6 ·
You might be better off with dual exhaust to help with scavaging, however in my honest opinion I hate the sound of dual exhaust, now if you throw a H or Y pipe then it's a different story. If you want to get some gains in torque try advancing the cam a degree or two. To be honest in all the reading I have done along with the crap load of math I am still doing, you need to do more then change the exhaust system to gain some power, with these magnum engines the exhaust port is so small and the valve head diameter is small 1.8ish", the lift could be better. But remember what you do to the exhaust you're going to want to do with the intake pretty much. Most performance exhaust systems are selected for the cam and intake, this is why most cam manufactures say you need a performance exhaust for a selected cam. But I don't want you to really spend time or money on a cam.

Dual exhaust would be better, simply. But you won't gain a whole lot. Now if you maybe change something like the driveshaft to one that is lighter then you will have less rotational drag which will free up some hp that is lost in parasitic drag, you could gain up to 8HP.

Another thing you can do is to have smaller wheels, it will distribute more force to the pavement and also reduce the rotational mass and same situation.
 
#5 ·
It'd be about the same. The best possible dual setup would porbably have slightly more power and torque than the best possible single setup. Duals also add weight though, and money. Unless you want the look of duals, I'd stick with single. Keep in mind too that local exhaust shops usually don't use mandrel bends (which the stock pipe IS mandrel bent). If you go duals with crush bends I'd wager that it'd perform slightly worse than the single with mandrel bends. If you do shorties, y pipe, and muffler(straight through), a gain of say 20+ hp and torque should be attainable. Headers make a big difference.
 
#10 ·
This isn't grounbreaking info but I always welcome real world experience so I will give you mine. I had a 2006 4.7L with entirely stock exhaust. I had the stock muffler replaced with a Flowmaster Super 44 and noticed no change in seat of the pants power. After running it for about a year I had the Flowmaster removed and welded in a Magnaflow oval 18" muffler....the rest of the exhaust remained stock. I can honestly say that I felt a small increase in low end pull on the seat of the pants meter. It wasn't huge or anything but I noticed it. The best way I know to describe it is that the truck seemed happier, lol. As a bonus I also picked up about 1 MPG or so. The 2004 hemi I have now had a Flowmaster when I bought it but I will be replacing it with a Magnaflow muffler and y-pipe when I get the coin. I don't have any experience with the y-pipe yet but if you crawl under there and look at the stock one you will see it is extremely restrictive. Hope this helps.
 
#11 ·
So starquestbd22, according to you what you felt, the magnaflow muffler showed more power gains when compared to the flowmaster? Hmm... I wonder.. Is there a difference in muffler design between both? I should say: Is the difference in design that much greater or unique that one actually made enough power so that it could be felt by the driver??
 
#12 ·
Hmm... I wonder.. Is there a difference in muffler design between both? I should say: Is the difference in design that much greater or unique that one actually made enough power so that it could be felt by the driver??
flowmaster is a baffled/chambered design, magnaflow is a straight through design. magnaflow will make more power than flowmaster.
 
#13 ·
^^^^^ What he said. Maybe this will help.





The chambers in the Flowmasters give them that distinct "hollow" sound that FM fans love. Magnaflows don't really have that...in my experience the Magnaflow was deeper and had more bass to it.

Like I said above...the power difference wasn't night and day or anything but I did notice it. The truck would pull longer up a hill before having to downshift and just seemed to not have to work as hard to get around. I feel like I should add a disclaimer, lol. "Results may vary!!!" But I am a Magnaflow convert. The FM duals on my hemi sound pretty good but I think about what it will be like after I get the MF on it everyday.
 
#14 ·
starquestbd22. Its ok. Don't worry about the disclaimer. It's not like it was a dyno pull or something like that. Just a simple on seat and foot to accelerator difference that could have been affected by other things including ambient temperature, weather, tire pressure and the like. LOL.
 
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