A few years ago I did a 3" cat back with a si/do flowmaster 40 with 3.5" tips. I left the cats and everything else alone. I will be towing a #4500 camper this summer and want as much low end as I can get. I have alot of bolt ons (chip, pulleys, e-fans, 75m, t-body, intake). from my research I have read that you shouldn't go too large with exhaust pipes.
I love the sound I have and havent noticed much low end loss. But I would like to gain as much low end as I could. I just recently did a 4.10 gear swap with my 33"'s as well.

Should I go with a set of Pacesetter Ceramic or Ford Racing SS headers or maybe redo exhaust with smaller pipes. Maybe a 2 1/4 or 2 1/2. The guy that did the work the first time told me the stock 2 1/2" to 3" isnt that much of a change and shouldnt loose much low end if at all. He also said dont waste my money on hi flow cats unless I need them. he said the OEM ones flow pretty good.

I am only looking to gain as much low end as I could for towing.
what do you guys think?

 

You won't get much more power (at any RPM unelss you replace it with a $400 Borla or Magnaflow system. I'd keep what you got.

 

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u might wanna port ur intake elbow or have intake manifold work done that will help a bit but it can get pricey. yes headers will help JBA's or Gibson would be ur best bet. pacesetters are cheap even from the looks of em

 

I did port and polish my intake elbow when I installed the larger t-body.
So going to a smaller diameter exhaust wont give me enough low end to be worth the money spent unless I changed to a different muffler like Borla or magna flow?
And headers wont give me the low end I am looking for unless I spend $500 on JBA's?

No disrespect intended -
but dont all headers do the same thing regardless of how much they cost. I mean I am sure the JBA's are a better quality metal and better coating but arent they all just bent tubes?

And would changing the diameter of the exhaust only make a difference if I change the brand of the muffler from Flowmaster to a Borla or a Magnaflow?
So if I kept a flowmaster muffler and went with a smaller diameter exhaust system it would have zero effect on low end torque? but if I then used the smaller dia. exhaust and swap the flowmaster for a borla or magnaflow than and only then would I have low end gains?
Something doesnt seem right there.

How about question...
What would give me better low end gains:

headers vs. a smaller diameter cat back exhaust pipe?

 

What sized pipes do yuo have now? Do you have a SIDO muffler or two y-pipes or are you true dual?

If you are 3" now, going to 2.5" would probabyl get you more low end torque than headers.

 

You may want to consider and X/H Pipe. This will equalize the pressure between both banks of the engine, and give you a little more HP and torque throughout the RPM range. They are reasonably priced, and easy to install.

The correct pipe diameter depends on how many horses your pumpin out. 3"Inlet/2.5" Outlets is about right for a 5.4L.

http://www.magnaflow.com/07techtips/faq/question10.asp

If your exhaust pipes are correct, you can simply replace the muffler if you want, you wouldn't have to buy another CAT-Back system. You can go to a local Mag/Borla Dealer and pick up a universal muffler pretty cheap. I think mine were $65 a piece. ( pn 12225 )

 

But that won't get any more power alone.

With the mods he has, changing the exhaust at all will yield very little difference in towing power. For 4500 pounds, there isn't much point to spending as any stock V8 F-150 won't have a problem with that much weight, let alone with mods.

If he wants a lot more power, he'll need to buy a Superduty w/ V10 or PSD.

 

u could also get one of those high amp loud as hell electric fans... that give like 1-2 PSI boost... they arent reliable but do work lol

 

I have the 4.6L motor. I had a custom hi flow" "y" pipe made and the exhaust is all 3" from the Y back. I ama not sure on the dia. of the "Y" pipe but the single inlet on the muffler is 3". The muffler is a flowmaster 40 series si/do with 3.5" tips.
so if I went went with a 2.5" head pipe (pipe rom Y to muffle) and a new si/do muffler with 2.5" openings and kept the 3.5" tips that would help me produce more low end torque.

I am not even sure I need more power since I havent pulled the trailer yet. Picking it up a week from Sat. I am just looking to see if maybe I went with too large of an exhaust and if redoing it would help me get some inexpensive low end power.

 

A 3" intermediate is the correct size for your truck. I would just replace the muffler with a Magnaflow 3"SI/2.5"DO.

You're looking at around 15-17 HP with a Magnaflow.

 

can u post a dyno sheet to show that the magnaflow has better torque increases then the usual muffler selection .. being that its a straight through design eliminating most all back pressure? u would yes see HP but u would loose low end torque...

 

Muffler alone, no way. Cat-back system sure.

 

Changing a baffle style muffler out with a straight thru design will INCREASE low end performance...

he has all the piping already, just need a straight thru designed muffler... it will definantly increase low end performance.

 

APT,

He has the correct size Intermediate pipe already. If you don't believe me look it up yourself.

If he wants to add some more low end, and a little more HP, then he needs a high flow muffler. SI/SO would be best performer and cheapest but, since he wants to keep his duals, he will need to swap out his 3" tail pipes to 2.5".

So lets recap...

New SI/DO Muffler (Borla, Mag, or even Dynomax) $85-$100
New 2.5" tail pipes. $50-$100

so for $200 or less, he can have a high flow exhaust system.

Or he can follow your "advise" and spend $400-$500 on a completely new Cat Back system.



FasterF150,



Although, I'm sure magnaflow actually saw these numbers when they did their testing, I don't know that I would bank on it. I would , however....bank on what Troyer Performance says...

http://www.troyerperformance.com/cgi...atalogno=15609

"Power gains typically average about 15-17 HP (flywheel) on the 4.6 & 18-21 HP (flywheel) on the 5.4 motor. Thanks to the largest peak power gains as well as more torque at any throttle position or rpm, this cat-back system is literally perfect for any kind of use, typical daily driver, *great* for towing, all the way up to actual drag racing, this exhaust adds more power all the time in any situation."

I'm curious, what makes you think that you would loose low end torque with a better performing exhaust system?

Blank21,

As you can see, you will get all sorts of advise from folks here, some good some bad. I suggest you take all of our suggestions put them in the back of your mnind and do a little research for yourself, and make a decision based on what you find out to be most accurate for your needs. You're the one spending the money, and driving the truck.

Good Luck!!