OK, I am thinking about an exhaust to replace the restrictive OEM one.

Ok I read ALOT of posts by you guys to sort of "catch up" and I read alot of horsep[ower and sound gains but not to many folks mentioned the backpressure. With a high flowing exhaust it'll reduce the amount of backpressure and therefore make your torque go to hell when you need it to carry its big *** body...

Some guys say gut the cat and have no muffler. I haven't heard anything so rediculous.

So, in realistic terms what could I throw on?

I am narrowed down to a flowmaster and a glass pack. I do not have alot of money right now. The flowmaster will cost $140 installled. And the glass pack $50.

I could care less about sound. Its an expedition. My main thing is to make it get better gas by as much as you can with this mod and to gain some performance.

With flowmaster does the performance everyone talks about mean less fuel economy?

I have a K&N cold air intake. It sucks in easily but it can't expel it. SO if I throw on a glass pack I think it'd be more efficient.

I asume ANYTHING would be better than the restrictive stock muffler.

I don't have the big dollars like some guys to just replace the entire systems piping and muffler for $950 and all that. Hell not even $400. You saw the price i am working with. the Glasspack or the flowmaster. If the flowmaster is not all that far off, but will bth increase the fuel economy by about the same and the performance will be minute, then hell, glasspack it is.

Also, whats the difference b/t a cherry bomb and a glass pack?

thx

 

Backpressure is a myth, at least as much as it being good for performance.

If your budget is under $150, buy any straight through muffler and replace the OEM one. I prefer Magnaflow. Flowmaster, despite its name, doesn't have the best flow, or the best longevity with the baffles inside. A 5x8x18" oval aluminized Magnaflow muffler should cost about $75 plus any local shop can install it for under $50.

I would not expect any better gas mileage from just a muffler swap, though. Some people get something, but most stay the same. If you only care about how much fuel you'll be saving, save the $125 for fuel, not the muffler.

 

at the gas saving tip...

But what about this. Restrictive muffler, equals harder strain on the motor to push out the exhaust. If its easier, the motor will not be as hot, heat destroys horspower. So if you have more horse power it take much less to get it going. Therefore less strain on the motor, therefore you save gas. Its a cycle. Ad I replaced the air filter with a K&N cold air intake so the air can suck in but it just can't get rid of the excess fast enough.....

How do you figure the backpressure is myth? Cut your mufflers off, cut the cats off as well, and do a dyno test....

See if you have as much torque and horspower as you did with them on.....

 

Backpressure is tossed around quite a bit...it's never good. Backpressure is restriction, and you don't want restriction in the exhaust.

What people really mean is, you need good flow. If your system is too open, the exhaust gasses cool within the pipes before they are expelled. Cool gas is more dense, so it takes energy to push it out.

A proper setup means the exhaust gas retains enough heat and energy and gets out of your system quickly. Also, there is a scavenging effect, where the gas leaving the tailpipe effectively "pulls" other gas through the system.

This is overly simplistic, but you get the point. Too much flow = cooler gas = denser gas = harder to expel.

But it's just easier to call it backpressure, for what it's worth.

 

I had an aluminize Magnaflow installed for just under $100 at a local muffler shop.

part #11236

 

[QUOTE]Originally posted by APT
[B]Backpressure is a myth, at least as much as it being good for performance.

Ok, this is a statemnet that could cause someone to make a serious mistake. Imagine if you took one of these stock trucks, even with a real good cold air intake ( which by the way BB123, if you bought a K&N, you way overpaid and got a piece of plastic that is not any better than most performace intakes) and installed a 3" true dual setup with headers and highflow, or even no cats. What would happen to this poor smucks motor within a years time? He would blow it, thats what. And in addition to that, his torque would be non existing. True, backpressure is a tern used for the sistuation of the air moving out keeping warm enough to allow for minimal resistanceon the motor and not a certain amount of actuall pressure applied to the to the exhaust forcing it back into the manifold. But however someone labels it, I it vital that a pre-determined minimum amount of restriction be placed on the airflow. There ar alot of things I would love to do to my exhaust to add sound, but I know it will only damage my engine or at a minimum, decrease my torque.

 

To follow JordannotMike...

The only thing that matters for performance is speed of the exhaust flow. Larger pipe diameter = larger cross sectional area which means the speed of the exhaust is lower. If one goes much larger than the optimal pipe diameter, he has to compensate with resctictions (often called backpressure). True dual pipes with no cats or high flow cats does not kill low engine speed torque, as long as the diameter of the pipe is matched to the motor.

 

So in other words, here is the breaking point...

If everything is left stock. Besides the K&N filter cold air deal. Oh yea, and S_U_R_F, no i did n't buy the whole K&N deal. I compied what was posted on here as a do-it-yourself type job and used my K&N filter, cut the housing away, and left the sensorsetc, the same...

OK, if everything is stock besides the Filter...

- get a glass pack. It'll create enough backpressure, or enough suction to keep the gases hot and not cool them off...

The stock is too restrictive so get that as its prob cheapest.

-is flowmaster muff going to make that much of a difference over a glasspack for what I am after?

Basically, I am in a financially tight situation with x-mas, college, and bills in general I don't have a whole lot to spend.

So what is the cheapest most effective way? Glass pack installed for $50? I am not going to drag race so does it make a differnce? I hear its old technology...

Give me your best advice of a money tight situation and what you'd do that is going to help the vehicle ( the hell with sound...its nice but that's not my motive)

 

Looks good big dawg

 

Spend $50 on a glass pack now will get you just as much poerformance and fuel economy as any other muffler alone swap, which is minimal.

 

hey i have the 5.4 in my 00 f-150... all i have is the stock manifolds, cats, down pipe, but cut off the orginal muffler and put a flowmaster 40 series single inlet dual outlet . as far as mpg...id say averaged about 1 and i mostly do city driving ... hp gains were minimal at first, i added a cold air intake and it worked well together and got maybe.5 more mgp and more noticible power.... i could be wrong but from what ive hear NOT EXPERIENCED is taht some air filters let enuf cold air in that it costs u mpg, dont kno if this is true. the reasoning i heard for it was the more air u put in the engine the more fuel that has to mix with it...so it sounds like a decent argument...but of course with the more air and more fuel you get more power which means your truck has to work less. all i kno is that with a open element filter and intake elbow mixed with my flowmaster muffler scored about 1.5 city mpg and a little more power. if you want a cheap way to get flowmaster serch EBAY i found mine there brand new for 27 plus 15 for shipping.

 

In my opinion, the factory collector/y-pipe (where the exhaust from each bank merge into one) is the most restrictive part of the system. When I removed mine, the interior hole was so small I could barely get a finger into it.

If all you want is less restriction and are on a budget, replace this. They are only like $30.

I'd buy the muffler for sound. I personally don't think there's a significant difference between mufflers.

 

Interesting.

What about HKS? You being in Cali know all the ricers that mob around in the imports.

They make a great exhaust for those, now how about an American motor?

Look at this.

http://cgi.ebay.com/ebaymotors/ws/eB...MakeTrack=true

 

your pretty much the same as me.

I have a 5.4L 99 Expy. Right now gas is a bitch. 8.6-9.5 mpg. Is this about right? Or does something seem wrong. Its a 4X4 too and there is no 2WD option. It goes AWD, 4H, 4L. SO technically I am running in 4X4 ALL THE TIME?

Can I expect what everyone else that I speak to gets? They claim 22 hwy and 16city....

Or are they really full of ****.

I have a electronic deal that tells me the ave gas mpg's I get that is facotry withthe eddie baeurs...

Are the accurate or full of *****?

 

if I let them know they should know what this is and what to replace it with right? What shoudl I tell them to replace it with?

What dimensions I mean. Then I should have them throw on a glass pack as well. But doing the muffler and the y-joint will this leave too much air flow and the exhaust gas to cool instead of stay heated and get sucked out?


Also, an imprtant factor. If I buy online I need to know which one. Whcih style do I buy? center inlet, or to the side it center out or?????

That is one confusing issue for me right now in selection of a good online deal on ebay...

thx man...