I hope I do not offend anyone, but I think we need to clarify for the newcomers what a Dual/Twin exhaust system is.

A dual/Twin exhaust system is a term that was used beginning back in the 1940's and Means that a separate exhaust pipe is used to expel gases from each cylinder head. Within this system, additional components to equalize pressure may be installed which by today's terms are called "X" or "H" pipes.

A Cat-Back system removes and replaces the exhaust system past the catalytic converters. In many cases dual tailpipes are included as part of the package and may include dual mufflers. But this is not a dual exhaust system.

Although a true dual exhaust system will provide excellent benefit to the performance of your vehicle and sound for that matter, it is important to realize that when it comes time for the smog certification, unless the factory installed a true dual exhaust system on the vehicle, and you created a true dual exhaust system on your vehicle, the technician is required not to past your vehicle and in most states police may impound the vehicle for such blatant violations. This is not to say that a cat-back system that runs dual tailpipes is not technically in violation of some Environmental Law, I have yet to meet a technician or police officer who would cite someone for having this setup. but you must also be aware that removing/replacing the factory catalytic converter prior to five years or 50,000 mi., unless it has been damaged, is illegal and technicians required to monitor for this also during the routine smog inspections. Just my 2¢

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Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II

 

Terrific description of duals, but your last paragraph lost me. It may be "technically" wrong to switch to true duals, but there is no need to add/remove/alter the configuration of the vehicle's catalytic converters. True duals IS a cat-back mod.

Besides, sssshhhhh.... the OK state inspectors might hear you and stop passing my vehicles like they have done for the past three years!



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1997 4x4 Expedition- 4.6L, true dual exhaust w/glass-packs, K&N air filter, SuperChip, airbox mods, Edelbrock shocks, 285/75R16 BFG ATs, 2000 "XLT" wheels, 4.10 gears, Auburn LS, Clarion In-dash CD player, Smitty Bilt push bars and nerf bars.

2000 4x2 F150 XLT Reg. Cab LWB- 5.4L, Tow Pkg, 3.55LS, CD player,Remote Keyless Entry, Sliding back glass, Special Appearance Pkg., tinted windows, Line-X bedliner, and Prime #155 wheels.

http://members.visualcities.com/NoMo

 

You are absolutely right!!!there is no reason to remove the Cat's. On some cars/trucks, the head pipes come into a wye (2 into 1) to run the exhaust through the Cat's, I have a friend who didn't believe me, added a second head pipe, another cat and low & behold failed at the Calif test and now (because it's on record) has to go to a Fed referee station for his smog certs from now on....OH!

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Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II

 

Someone may have to clarify me on this, but I believe you are wrong, wrong, wrong....

If you look at the exhaust on our trucks, at least the V8's it is set up like this:

[code] ______
__ __ | |
---|__|---|__|-----| |------------
| |______|
|
__ __ |
---|__|---|__|-|[/code]

As you can see we have catalytic converters and resonators on each side BEFORE the single muffler. So you are not altering the environmental aspect of the exhaust system one bit by adding true duals in the following manner:

[code] ______
__ __ | |
---|__|---|__|-----| |------------
|______|

______
__ __ | |
---|__|---|__|-----| |------------
|______|[/code]

You are not removing or adding or changing anything until after the cats. I don't know if California has some kind of rule to prevent you from doing this, but I'm sure most states do not.

Thanks,


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Chris Thomas
<A HREF="http://216.147.104.171/Y2K/members/ChrisT/christ1a.jpg" TARGET=_blank> </A>
1998 F-150XLT Flareside STX Sport Package, 4.6L Auto 3.55 Oxford White/Gray interior, Factory Anti-theft system
Picture: http://216.147.104.171/Y2K/members/ChrisT/christ1a.jpg
Homepage: Chris & Brandi's Universe
Mods: A.R.E. Decklid/Oxford White with gray fabric liner, K&N filter with Airbox Mod (removed silencer), Lowered 3" front/5" rear, Tinted Windows, GTS sloted taillight covers (painted Oxford white to match), Removed STX stickers
Audio: Kenwood Truck speakers with 10" woofers, Rockford Fosgate and Alpine Amps, Ford 10 disk CD changer
Future Mods: 20" rims and tires, True duals with Supertrap tunable mufflers, Superchip, Supercharger, Jacobs Ignition, and whatever else I can think of!!!

[This message has been edited by Chris Thomas (edited 04-20-2000).]

[This message has been edited by Chris Thomas (edited 04-20-2000).]

[This message has been edited by Chris Thomas (edited 04-20-2000).]

[This message has been edited by Chris Thomas (edited 04-20-2000).]

 

Here in SC they don't even have safety inspections much less smog.
NO INSPECTIONS at all !!!
We used to have safety inspections, but Evryone knew sombody that would put a $3.00 sticker on it for them.
It was a joke so they stopped it.

 

On earlier models including V6 & V8 cars & trucks (including V8 Mountaineer/Explorer) Ford has two headpipes that come into one pipe, connected to up to three cats, then wyes into two tailpipes. You're right also, that if the vehicle came with separate cats on two separate head pipes, you've got duals & they are legal to increase pipe size, tailspipes, mufflers, etc!!!

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Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II