I'm getting ready to install two Series 40 Flowmaster Mufflers right behind my dual Catalytic Converters. The mechanic didn't indicate that he thought it was necessary to install a "Cross-Over" tube between the two exhaust pipes. Does anyone know
if this makes a serious difference to a 4.6? I notice that all the
professionals seem to install a tube that equalizes the exhaust
between the two pipes. Maybe my guy just doesn't care? Maybe
it really doesn't make any difference? Does anyone have some
information on this?

Bill

 

It'll cost more to do, but I would have it done. It'll help any size V-type of engine. As you say, it 'equalizes' the exhaust. I think it especially helps the low end torque.

 

Installing the crossover pipe is a good idea. I hope you like your trucks loud because that's what it will be with series 40 flowmaster mufflers. I hope your fillings are in tight because they will sure get rattled at around 2000 RPM.

Just my two cents BUT...

I know of two guys who installed the 40's and then later changed them because they couldn't stand the noise inside their trucks at freeway speeds.

 

The balance tubes help to even out the pulses in the exhaust gases and balance the backpressure between both banks of your engine. They help improve sound and HP.

 

Thanks guys. Now, I just have to decide whether the series 4o
is going to be too noisy or not. I could go to the series 50 -three
chamber mufflers. I heard a guy with 40's on his ford car and it
wasn't loud at all. But each application is different. I have twin
cats and who knows what he was using.

Location has a lot to do with it too. Since my twin catalytic converters are up front, the only place to install two mufflers
side-by-side are across the drive shaft from the gas tank. That
puts the noise mostly under the bed of the truck. Under the cab
would be a bonehead mistake.

The guys who got rid of the 40's may have not had twin cats and may have installed the mufflers farther forward. Do you know
what the actual situation was?

Thanks again guys,

Bill

 

To: Bill Voyles-

Concerning the two guys with the 40 series flowmasters: Both these guys had the mufflers installed in about the same place as the stock muffler was installed. That put the mufflers under the rear door on the extended cab truck which both of these are. One of the trucks is a '97 with a 4.6 like mine. The other truck is a '98 with a 5.4. You can detirmine the number of cats on these trucks, I'm really not sure as I sit here typing. One of the trucks had the pipes exit in front of the rear wheels. His truck was really loud when you were sitting inside. The other guy had his pipes exit father to the rear behind the rear wheels, not under the bumper. His truck wasn't quite as loud when your were sitting inside. From the outside, both trucks sounded about the same. The truck with the longer pipes may have sounded just a bit more mellow but not much! In either case, these trucks were a little too loud for my personal taste. One of the guys had a problem with triggering his neighbors burglar alarm about half the time he started his truck. I think maybe the alarm was a little too sensitive but I could start my truck and not set it off. I have a single 3 chamber flowmaster with dual outlets.

Both of these guys complained about the noise they got at about 60 MPH on the freeway. One guy told me he solved that problem by never driving at 60 MPH, no kidding!

You should keep in mind that the above occurances happend over the last two years or so. I know that Flowmaster mufflers have changed so maybe none of this still applies. I think at one time the 40 series mufflers were two chamber units and that was the reason they had such a resonance at certain speeds. They now have the Delta series in the line. All this that I've written is simply to give you some information to check out for yourself. Ask the right questions and all that. I hope this information has been helpful.

 

Definately, use a cross-over tube of some sort, I prefer the "X-Pipe". Prefab, easier to install, smoother transition, etc. As far as FM 40's being loud, well, they are loud, and at the same time, their way too quiet. It's all a matter of personal preference, piping, tip size, etc. With 4 cats, it's not possible to get these babys really loud, even if cut off right after the last cat on each side. I'm running 3" straight pipe, and turned down before the axle, and I have ZERO drone, and with windows up, theirs almost nothing there. Also, when you put duals on, and a muffler on each pipe, it's actually quieter than a single pipe with one muffler. Also, tips make a HUGE difference. The longer, and bigger, the deeper, and throatier. The really do act as a magaphone.

-AR

 

So would a single tube with one muffler be the loudest? Would a SI/DO with an FM40 be louder than a setup with an X-pipe and two FM40's? I really want a dual exhaust so any input on the loudest setup would be appreciated!

 

...the loudest setup would be true duals using an "X-Pipe" no mufflers, with 3.5" x 26" stainless tips angled downward before the rear axle.

-AR

 

True True but i really need a legal setup. So which is the loudest setup with mufflers?

 

...reversed glasspacks, or install them correctly, and get em' hot...then hose em' down with cold water.

-AR