Creating Dual Exaust
 

Can someone tell me what is needed to do this on my 2007 Monte Carlo LS 3.5 V6 and what you gauge the difficulty at? :nono:

Besides buying the kit/system itself, which I know. But I mean the installation, what is needed to do this successfully.

Are you talking about true dual exhaust where each cylinder bank runs back with its own tube, or dual 'looking' exhaust where you have a single pipe running back but have two mufflers/tips at the back?

If it's the latter, why not just take it to an exhaust shop and have them add a second muffler for you? If you like the stock muffler, you could just bring a stock muffler/tip from a junkyard and they could weld it up.

If you want more sound, you can have them just cut the pipe off after the rear suspension, add a y pipe and then weld up whatever mufflers and pipes you want.


If you want true dual exhaust, id try to talk you out of it based on complexity and cost for minimal gains.

NO, NO, NO, I need TRUE DUAL, MORE POWER.

I was first going to cut the stock muffler for a new performance muffler. Ideally I would like to true dual with two identical performance mufflers.

Let's face it, short of supercharging what I have, everything I do is going to be a minimal gain. But a bunch of minimal gains together is not such a bad thing. But in the future if I am able to supercharge, I am sure a true dual exhaust is going to be a benefit.

How much horsepower do you actually expect to gain by installing true dual exhaust? The factory catback isn't particularly restrictive on a near stock engine, so adding a performance muffler alone, changing to a big 3" single, or to a 2.5" true dual is going to have minimal gains. I would bet when finished, you're talking less than 10 crank hp.

Also, have you considered that virtually no one runs true dual exhaust on these cars? There are a few reasons:
-Cost. No one makes a bolt on true dual exhaust kit for the wbody, so it will have to be totally custom. An exhaust shop could bend up the piping, but you'd be paying double what someone wanting custom single exhaust would pay. To get it all done with mandrel bends for the best performance, and with all stainless components (so it will last), I bet you'd easily be over $1000. Try pricing out two stainless mufflers, resonators, cats, and tips- I bet you'll find that you're and easy $500 there and you don't even have tubing or labor yet. That's also implying an exhaust shop would even touch this. Relocating emissions components, and messing with the exhaust manifold outlets / creating downpipe is outside of the scope of most simple exhaust places - you're talking more of a custom fab shop

-That gets me to my second point, labor. Everything behind the cat should be fairly simple. It'll be a lot of work to get the packaging right so you don't lose too much ground clearance, but it's certainly not impossible. The hard part is positioning everything up top and making two downpipes fit in a hole made for one. It'll also be hard to fit two cats in there unless you use some aftermarket minis that are staggered.

-weight / hp. Double the components means double the weight. I'm not sure what a catback usually weights, but a quick Google search shows 40# for a few single exhaust cars I searched. You're going to need double that weight to have duplicate conponents. Are you sure the minimal power gain won't be more than offset by adding that much extra weight? It certainly won't be a trivial amount, and it also won't be over your drive wheels to help provide additional traction.

-design. Certainly any exhaust shop that will take the job can weld some pipes together to make the exhaust come out of the back of the car, but to do it 'right', and get the sound dialed in, you really need someone who understands exhaust sound and flow, not just your typical muffler shop. Size of piping, type and location of crossover (h pipe or x pipe), component locations, where to put the single o2 sensor, etc etc all should be considered by someone who knows what they're doing so you don't end up with something that sounds or performs worse than stock.


If you have a desire to supercharge it, a mandrel bent 3" or even a cutout dumped ahead of the exhaust would both flow plenty for the supercharger.

I think the main thing this boils down to is that the horsepower gains are far too minimal compared to the added weight and huge cost to do it right. For the money you spend on this, you could easily buy a nice nitrous kit and make 10x the power gain.

Thank you for your information. I do not know anything about it, that is why I made the post. I assumed or thought it may have been a pleasing gain in power. I guess to go the cheap, quick and easy route for now would be to cut the current muffler off with that zig zag pipe underneath, make a straight, even shortened pipe to the new performance muffler? What do you think of this idea?

In general, the power gains from exhaust work in the catback are minimal on a nearly stock engine. Even the best flow solution (albeit not the best for managing exhaust pulses) - being a cutout or removed catback - gains comparatively little power.

IMO, I would suggest selecting aftermarket exhaust components based off of what sounds best to you (youtube is a great resource for this). The difference between one aftermarket muffler and another is going to be nearly nothing, so youre best off picking what sounds the best to you instead of trying to chase an extra couple horsepower since you will have to live with that sound everyday. You'll be kicking yourself if you gained 2 extra horsepower but the drone on the highway gives you a headache.

When you talk of a stock engine, what else can be done to make it less stock? Does that include changing the headers? Adding a CAI? I have done the CAI. I am getting interested in headers changing. (I am a little appalled by how much this car weighs.) Going back to the performance muffler, I think a change in that from the stock one can only be a sound improvement.

When I talk about a stock engine in relation to upgrading exhaust, I mean that the engine mods done have little impact on the total airflow. Adding a few simple bolt ons and picking up say 10 or 20 horsepower doesn't translate to a big delta in the airflow coming out the tailpipe. As the stock exhaust isn't particularly restrictive on a stock engine, it also won't be particularly restrictive on a simple bolt on engine.

When you really start to see gains from exhaust are when you've done something to dramatically increase airflow through the engine (heads/cam/headers, supercharger, turbocharger, etc). These mods can add say 50% more engine power, which results in a lot more exhaust and thus makes the stock exhaust much more of a bottleneck.


As for headers, you typically can see decent gains from a header swap. However, I didnt know they made headers for the 60 degree v6. The difference with changing headers vs changing stuff in the catback is that there are a lot more variables to play with to tune the engine for what you want to use it for when dealing with headers. The manufacturer tries to get the exhaust to hug the engine as much as possible for packaging purposes and to make it easier to stick the engine in during assembly. They are also very concerned about NVH since most people don't want to hear engine 'noise'. You don't have to worry about those requirements, so you have more options that can pick up power.


As for the weight of these cars, that is another great performance option. Less weight improves all aspects of vehicle performance. The car accelerates quicker, stops quicker, and tends to roll less while cornering. Also, less weight helps prolong the life of suspension bushings and braking components. The problem is, most people don't want to do it takes to cut weight. There is a lot of stuff you can get rid of for free to cut weight quickly - heat, air conditioning, radio, extra seats, carpet, etc are all totally free and have substantial weight. Cutting weight without removing stuff can get expensive though. You can get composite body panels, polycarb windows, and start replacing cheap/heavy materials with lighter and more expensive materials (like the aluminum cradle upgrade for older w bodies).

The more you share the more overwhelmed and confused I get. Not saying it is a completely bad thing because learning things is a good thing. So much like no downpipe upgrade for me, is there no headers upgrade for me? This would blow.

There's really no need. You aren't pushing enough exhaust out to require the headers. If you went forced induction, you might need larger exits, but for right now you would be fine.

I would say, you aren't going to gain anything from the exhaust system, so just go with sound and looks. Get a Y-pipe added, so that you can get 2 tips out the back, get nice tips, and use the mufflers that you think sound the best.