Dual exhaust conversion
 

I have 08 grand marq. I would like to put dual exhaust on it. The rear bumper has a cut-out for another tailpipe. Anybody done this? tips would be greatly appreciated.

Marauder and police have it... i am sure a typical exhaust place can do unless you get parts to install yourself

I know walker has a dual exhaust kit. Like 87 CV said, about any exhaust shop could do it. You just need an H pipe connection from the cats back, & a right side exhaust pipe & muffler.

Many CV owners find a used dual exhaust system from police cars in the wrecking yard. They have the advantage of being stainless steel & should last a long time.

It will increase your higher end horsepower, but my experiences is that it causes a slight reduction in low end torque. And the dual exhaust will have a louder sound, which some like, & some don't. Like everything, there is a compromise either way.

if i remember right, your body style started in 98... so 98 and after police or marauder cars would work in your car from junkyard... not sure if under car is same from 92-98 or i would say compare a 1992 to yours and look at hanger bracket points on your car to the older 4.6 cars...

i have a 99Gm LS and i have two inch duals from my headers back no cat/converters sounds amazing good gas mileage, a little less low end tq like Bulldozer says but enough top end hp and tq to chirp the tires going into 2nd, grows at idle Roars @ WOT

Hey Syracuse just did my 2008 Grand Marquis LS yesterday converted from single exhaust to true dual exhaust. Went on eBay ordered the H-pipe from walker 2 Cherry Bombs 2.25 Glasspack mufflers hangers and left tail pipe and two 3.5 chrome tips flushed exactly with the bumper. Took it to my exhaust guy charged me $300 to do it. Man it sounds like a beast. Nice deep rich tone and rumble on the outside I get a lot of heads turning when I drive it. Not much drone inside the cabin you can still have a normal tone conversation with someone in the car. I kept all the cats intact so it can pass emissions here in PA. Plus I also have a cold air intake system by AFE. I get no check engine light what so ever with this system. A lot of people were complaining about the K&N system kept giving the Merc's from year models 06 to 11 check engine lights. Far as the horsepower I went from factory stock 224hp and bumped it up to 260hp and Torque factory stock was 275 lb ft and now it's bumped up to 310 lb ft. Definitely woke up this big car for sure. I have to take a pic and do a sound video of the exhaust start it up and rev's and inside the cabin.

Dual Exhausts
 

Hello, Roman, and welcome to the Mercury Forums --
There's nothing quite like a nice-sounding set of duals on a V-8, and it seems like your choices were spot-on.
The Walker H-Pipe = low cost, well made, fits perfectly, EZ install.
Cherry Bombs = low cost, durable, good rumbles.
2.25-inch diameter = good combination of flow vs. scavenging effect.
Glad to see that you were wise enough to KEEP THE CATS in place. CAT removal is illegal, and STUPID, too.
The 300-dollar charge to weld it all up was pretty expensive, in my view.
I got all my exhaust system parts at Amazon.com, and got it welded up for 140 dollars at MufflerMasters, Avondale, AZ.
Your engine has more power than The 95 MERC -- your larger diameter pipes are necessary for maximum flow,
but too large of a pipe diameter will result in lost power and torque in the mid-range rpms.
The Cherry Bombs should have a body length of about 18 inches (or more) -- too short will make for bad droning on the Turnpike.
The 95 MERC has a 2" system -- Walker H-Pipe; 2" x 21" x 3.5" MagnaFlow aluminized Glasspacks; Walker Tailpipes; Superior 2.5" Tips.
The 95 MERC was set up with an eye on long-distance, high-speed cruising throughout the deserts and mountains of the America West.
As installed, the system delivers increased performance, increased fuel mileage, V-8 rumble, and NO droning at Interstate Highway speeds.
My exhaust system yields 24 hp over stock, checked with G-Tech Pro. TOTAL cost was just 285 dollars, installed.

https://cimg2.ibsrv.net/gimg/www.mer...4bb0ae04f0.jpg
Walker H-Pipe; MagnaFlow Mufflers; Walker Tailpipes.
https://cimg1.ibsrv.net/gimg/www.mer...f27ccadd45.jpg
Custom Dual Exhaust Exits; Superior Tips
After welding up, entire system was coated with VHT Hi-Temp paint -- looks great, sounds great, and there's money left for Bourbon and Sour Diesel. ;>;)
If you can, take a few flicks -- and send 'em -- wanna see that Cold Air Intake installed -- and the Duals, of course !!

Does anyone have a list of dual exhaust parts to order (THAT FIT) from Amazon. I have a 2004 MGM.
Thanks all.