i have been looking around the web, and i have not found anywhere that sells true dual exhaust. they have dual outlet, but ont systems with 2 mufflers and all that good stuff. does anyone kno of anywhere that sells actual dual exhaust? i am tempted to just buy some good headers for my truck(f150 supercerw '01 5.4L) then just put the mufflers dirtectly onto the headers, no cats, no sensors, nothin. but i dont kno how great that would be. any advice would be greatly appreciated.

 

An exhaust shop can do anything you want. I am sure a quick stop at any of them can get you a quote. If you want a complete system from a manufacturer, then Bassani is the only one I know that would be close.

You cannot go without at least 2 oxygen sensors. They have a large impact on the air/fuel ratio.

 

you want true duals-go to a shop and get a custom setup. You can eliminate your back cats but you have to have O2 sensors or your truck will not run right. These engines are very oxygen sensative. You could always get hi flo cats and run true dual straight pipes, which is what im getting ready to do.

I like your name by the way

 

so even if i take out the cats, i must have the o2 sensor? i was looking to pay under 350$, and i have heard that the custom fabrication would cost muco denero. Green, the original plan that i had was to remove all smog equipment, including pump, cats, and o2 sensor, and get some shorty headers, or hooker comp, then run dual strait pipes, like on classic cars. then once i have to get it smogged, put the stock set back on. but from what everyone is telling me, i take it that the EFI system needs the o2 sensor to function correctly? that you for all of your help!!

thanks Green, i like the name too

 

If I am not mistaken, your O2 sensors are basically thermocouples. Higher temps mean you are lean and your computer compensates by adding fuel to the mixture. Low temps mean your are running rich and it does the opposite. So I believe (and this is only my theory) that these engines won't run correctly without some sort of oxygen sensor. They will search for setpoints and will not be able to find them in order to adjust the fuel mixture. I am only a shade tree mechanic and I don't even play one on T.V. Just my 2 cents. By the way, I had the Y pipe cut out and true duals installed from the "Y" out the rear with 2 magnaflows for $350.00. I have talked to them about stainless cats, mufflers and duals to replace what I have but that will run about $1000.00. Consequently, I would be interested in an affordable DIY stainless system myself.
Rick

 

O2 sensors are not thermocouples.

Anyway, $350 can be done. A DIDO Magnaflow muffer costs aout $125. The two Magnaflow mandrel bent tail pipes are $80/pair. Tips are $50/pair. Have a shop weld it together and add some extra pipe when they cut out the stock y-pipe. Really, not that difficult. You just only get aluminized pipes.

 

hey Rick, how come you want some stainless cats? dont cats only restrict the flow? why would you want that when you are adding dual exhaust to increase the flow? would it be possible to connect the mufflers directly to a set of headers, no pipes or anything? why does a EFI system need an 02 sensor to run correctly and efficiently when a carb set up doesnt? and i have seen carb set ups that make more HP than most EFI systems do. sorry if i am asking too many questions, i am kinda new to the whole modern car systems, i am more in tune with older cars (pre smog tech.) thaks for all of your help

 

I guess I cheated a little. I had a muffler shop set mine up. While I didn't do real Duals, they would have. They had a Magaflow set up that they were going to use. Because ours has dual Cats before the exhaust "Y's" together they can split it into 2 pipes. From experience with a Bullitt mustang with duals. If you go with headers etc you would have to get an error code eliminator. This kinda tricks the computer into "not" seeing any errors from the oxygen sensors etc. As a by product, we have found that with the code eliminators that if you live in a state where the inspections are done by plugging into the obdc II plug, that it will report back that everything is OK and pass without even having CATS.

 

Apparently my reasoning about the O2 sensors is incorrect, so I won't be much help there. The reason for stainless cats is that most aftermarket cats are supposed to flow better. I want stainless because it holds up better than aluminized steel over the long haul. As far as decreasing the exhaust restriction, these trucks are a little finicky. They need a certain amount of back pressure to scavenge or pull the exhaust through your system correctly. If you free the flow up too much, the gas won't be pulled through and your engine will bog down. Mike Troyer in the chip forum does a great job of explaining this. I found out he was correct when I put 2.5 inch duals on my 4.6. It ran like a dog. Went back and had it redone in 2.25 inch pipe and like magic the low end power came back. The 5.4 liter engines may be able to use larger diameter pipe, but it didn't work for me.
Rick

 

so if i take the cats of, and add dual exhaust, i would have to keep the diameter of the pipe small, or make the diameter large and get some high flow cats? from some reason that doesnt seem right to me, because you can used basicly the same motor, but with a carb, and have 3 inch dual pipes with super comp headers on a classic car. i dont mean anything of this in an offensive way, im just a little confused. thatks for all of the help

 

if you want to run with no cats like i am, then you need to use MIL eliminators, these can be bought off ebay or most mustang stores. these go only on the back 2 sensor and make the computer think it still has cats. the front 2 sensor dont have to be messed with as long as you put them back in. As for back pressure you will hear different things about what you should run. i currently have no cats stock y pipe with a s1/do flowmaster 40 out the side all of this done in 2.5" including the tips. it sounds good and gave me a nice hp boost. i plan to change to a new setup though.

 

The mil eliminators would be your best bet if you want to get the maximum flow from your pipes. Also, yours being a 5.4 helps. I know for a fact that mine ran like crap with the bigger pipes, but All my o2 sensors were in their stock locations. The stock exhaust system on these trucks is 2.5 inches through a single muffler and out through a 2.5 inch tail pipe. A better muffler, a cat back, or a dual set up the right size is great, but open headers or three inch straight duals with no mufflers won't benifit you at all. The principle is that some change is very good, but more is not necessarily better. Silver Bullit99 has the type of setup that works well for a lot of the members on this board. The good old days of long tubes, glasspacks, and big pipes are probably past us. If you want to run straight pipes with no cats or mufflers you can, you just have to size the pipes correctly. I'll see if I can find the article that explains the way the gas pulses through and scavenges the exhaust. It is very interesting and does a much better job of explaining the system than I am doing.
Rick

 

This little article might help a little. Also has a chart for choosing pipe size.

Good luck.

 

LE PEW,
Good article. Not the one I was referring to, but pretty much the same information. I like the sizing chart.
Rick

 

I left the stock CATS in place and went from the "Y" back with a 3 inch single exhaust pipe, out the side in the stock location with a 4 inch tail pipe extension. From what research I could do, I believe I'm getting about the same benefits as a true dual setup with 2.50 inch pipes. I have a 5.4 and it runs and sounds great. Gas mileage went up -- s l i g h t l y. This setup was somewhat cheaper that going with a true dual setup. Probably if you bought the parts and installed it yourself, it would be even cheaper. Mine just feels stronger and more responsive, but a lot of that could be just because I can HEAR is respond more.