I want to had some sound and some hp to my 04 4.6. Obviously the cheaper route is the muffler replacement and this is what I am considering doing. Will I still get about the same sound and hp increase with just the muffler?

 

You'll do better with the catback versus just the muffler. I've also got the 4.6 and a catback system and truth is I didn't notice a real difference in performance, but that's normal given the size and weight of these trucks. Probably be a heck of alot better combined with an intake and tuner. Good luck!

 

I've got the catback, intake, Superchips. If I was doing it over, I would probably just go muffler, pro installed. 18 inch Magnaflow if you like it loud, 24 inch if you just want a power sound, and a little more umph on the freeway.
On the 5.4 with extras, sure, open it up, but on the 4.6, it's got a pretty big pipe from the factory, just a heavy, restrictive muffler.

Chris

 

I just replaced the muffler, and slapped on a chrome tip. The full catback, from my understanding, will only give you a few more horsepower. If you have, or plan to add a supercharger, then the catback will be the way to go.

 

Let's face some realities...what's the difference between a Mag. SISO catback and plugging in the same Mag. muffler into the OEM system...nothing. Especially with a 4.6 engine hauling 5,600 pounds, any thought of performance enhancement is an empty dream. The best you can hope for is a satisfying sound improvement over stock, a change of appearance, e.g. SIDO rear exits or dual side exits, and perhaps (?) a fraction of 1 MPG increase.

 

I put the Magnaflow cat-back on my previous truck and the previous week at the track I was 17.0 - 17.1 consistent. From the exhaust install on I was 16.8s and 16.9s.

At those times it doesn't take a lot of added hp to lose some tenths but the exhaust did help. The cat-back exhaust came with a 3" pipe from the factory Y-pipe back. Mike T also said magnaflow is the only kit that didn't lose low end tq on these trucks.

 

There is a huge difference between drag strip and street driving.
Things that give you more ponies on the strip frequently cause your system to become 'peaky' or in other words, push your power-band up above the optimum range for street driving.
A 4.6 F-150 is not gonna be a good quarter miler, even with a supercharger.
Sorry.
If it's a-racing you will go, get a bigger motor. Or a much lighter vehicle.
If you want better miles per gallon on the freeway, better passing, more oomph pulling a grade, then putting on a nice Magnaflow with the stock pipe is the most bang for your buck exhaust wise.

Chris

 

I went the cheap route and just had my local muffler shop put a Magnaflow on. I went with the aluminized muffler, which still carries the Magnaflow Lifetime Guarantee (4" by 9" by 14" Body, 2-1/2" O/O) (part#11236) It gives plenty of sound when you get on it and has a real nice rumble at idle too, but no cabin drone at any rpm.

 

Just like others have said.. I'll say it again...
Naturally aspirated engines dont need a complete cat back system.. its simply not going to make a huge difference...

If super charging is in your future, then a dual exhaust, x pipe kit would be a must....
In my opinion... dont waste your money...

If you go to a muffler shop and have them just replace your stock muffler.... you wont see any difference in power... same as a cat back....

The intermediate pipe may not be stainless... but it will last atleast 4-5 years with leaks.. hopefully longer... and is CHEAP... $10 bucks and they'll weld in another brand new pipe....
The money you could save can be put towards more noticable HP gainers or HP appliers (e-fans, pullies, tuner, intake), (gears).

 

Are you saying the magnaflow will not add any performance to the 4.6? I am not wanting a race truck just a little more get up go for daily driving.

 

I'm not sure where he got his experience but I witnessed .2 of a sec loss on my 1/4 mile times with a Magnaflow Cat-back exhaust over just having the muffler cut out and a pipe welded in. I do have to admit that gave the truck a nice sound that I liked.

Upgrading from the stock diameter pipe, which I think is 2", to the magnaflow cat-back kit, which is 3" makes a nice difference in the flow. Mike T has even tested these systems and shows they don't lose low end tq like other cat-back systems can.

 

Not going to happen, these guys are right.

That little old 281 4.6L has plenty of snort for pushing a 2.5 ton truck around however, even light towing.
Best bet is a 24" Maganaflow muffler as Chris states for a nice low rumble and maybe a touch more performance/mpg on the highway.

Keep your foot soft and you will always go further on the same gas as a 5.4L.
These days that makes a huge difference... (and ususually gets you there the same time).

http://fordtruckworld.tenmagazines.c...muffler_intake

-Ron

 

I actually printed jpdadeo's pic and took it to the muffler shop. Good, cheap alternative to a cat back and I have a 5.4 with intake and tuner. Runs like a scolded dog compared to stock.