Doesn't seem to be too much for the 4.6L on exhaust wise. Everything kills its low end.

Did anyone do exhaust on the 4.6L which actually improved low end at all or didn't hurt it?

 

How about this?

Cut off factory y-pipe and run two 2.5" pipes to a dual 2.5" in/3" out Magnaflow muffler. Then use a reducer from 3" to 2.5" to use the factory tail pipe. Should open up the restrictions and yet be small enough to keep the exhaust speed up.

 

Intel486,
I just recently put an exhaust on my 97 4.6L. I am quite happy with the results and the price. I will cut and paste two postings that I made. One to tell you what the modifications are and the second to explain why I chose this set up.

-----------------------------------post one-------------------------------------
This is a bit lengthy.

Well now I have had my Magnaflow cat back on for just over a week, which doesn’t sound like much but I have put over 400 miles on the truck since then and also did some towing. Here is my impression.

If you’ve been following I previously had a Flowmaster 40 non-delta flow with basically stock out-the-side exhaust that came with my 97. It is a 2-½ inch system that empties in front of the passenger side tire. This was tipped off with a 4-1/2 inch stainless tip. It worked well enough and was VERY aggressive sounding.
I replaced that with a system that uses the Magnaflow 2-1/2 single in and duel out stainless muffler # 14218. I also went out the back with Duel Magnaflow 2-1/2 inch mandrel bent aluminized tail pipes #15020/15021. I finished this off with 3-1/2 inch stainless tips. I clamped the whole thing on since I have no way to weld the system (I used very good guillotine style clamps for good seal and no rattles).
***I have also gotten mixed answers when I asked if stainless can be welded to regular piping***
The exhaust in front of the muffler is the stock 2-1/2 piping that has been on the truck since new.

The first thing I will comment on is the obvious quality of the Magnaflow pieces.

The next thing I noticed is the Magnaflow system is much quieter in the cab. It is also not as loud outside the cab but more aggressive then stock. I actually had to stand behind the truck and have my brother rev it to see how it really sounds, and it sounds good. Gone is the annoying drone when I am towing.
When you really get into the throttle this system lights up and turns heads, but if it is NOISE you are looking for, then go with the Flowmaster 40 non-delta flow.

Third, I noticed an immediate increase in performance. This is supposed to be because of increase in backpressure but I can’t figure that one out. The Flowmaster is a chamber type muffler and the Magnaflow is a strait thru design. You can actually see strait thru the Magnaflow and if your hand was small enough you could put it thru the muffler. In contrast, the Flowmaster has “delta” chambers. If you ask me the backpressure should be higher in the Flowmaster.

...Now, back to the point…

There is an immediate sensation of better performance.
This is seat of the pants but there are also measurable differences as well.
Since the install, when I punch it from a standstill I ALWAYS spin rubber. With my set-up I did this most of the time anyway but now I do it ALL the time. I am running a locking diff so this is two-wheel rubber. Prior to this install if I was really hooked up to a good surface I may launch without spinning. Now I have yet to launch and not spin the tires if I wanted to.
Next when I bang second at WOT I always chirp second gear. I have a Trans-go shift kit and the Superchip installed and before it chirped about half the time. Now it chirps all the time.

In conclusion, I like the Magnaflow system. It combines good quality with performance and a healthy touch of that performance sound we all love.
The price was also excellent here
http://shop.ivalueinternet.com/bige...oduct_id/16.htm

----------------------------------post 2------------------------------------------
Just to explain.

When I did my exhaust I could have easily removed the stock Y pipe and gone with the DI/DO exhaust. Money was not an issue.
What worried me is I would loose too much torque.
I know people talk about backpressure, but more important (or perhaps the same thing) is the velocity of the gasses within the exhaust (speed at which the gasses move). Exhaust gasses moving faster produce more torque (to a point). Exhaust gasses moving slower-less torque. The factory Y pipe on my truck is really not engineered bad. The driver’s side enters at a 45-degree angle to the passenger. Both merge into a single 2 1/2 inch pipe, which keeps the speed of the gasses up. If you cut the exhaust in half in front of the Y pipe (true duels), there will only be half as much gas in the same size pipe so the speed of the gas is reduced, thus LESS TORQUE. With the 4.6L engine, I just don't think the engine puts out enough exhaust to keep the velocity up with true duels.
(My opinion, but opinions are like a$$ho!es)
If I had a 5.4L that is really opened up with ported heads, intake, MAF and headers, then I may have considered true duels. I think it would definitely benefit supercharged motors.

The Magnaflows flow without restriction, which helps with top end. By keeping the stock pipe in front of the muffler, I think I achieved the best of both worlds for my engine.
The sound is muscular under throttle.

I hope this helps.

 

I installet the Gibson Super Truck exhause on my 97 F150 with the 4.6. I love it! It was a bolt up, no cutting and it mounted using the stock hangers. The sound is great, I would recommend it.

 

Just installed the Gibson SideSwept last weekend. Not much louder than stock, but a little better sound. Engine is running cooler, first tank of gas was an MPG improvement (although it's a little early to tell for sure), easy to install myself (a little help from my awesome wife), and made some noticeable power gains off the line and on the highway. The power-band also seems to be a lot smoother to me.

The setup is a conservative SI/SO with 3" pipes. Supposed to give about 30% more flow. Coupled with a K&N, I think it's a pretty good setup. A little more air in, a little more air out... shouldn't affect low end. The Gibson setups are supposedly tuned for max low-end performance...

 

I have the Flowmaster 50 series SI/DO and didn't knotice any low end loss. When I pull the jet ski, however, I dont have a lot of power (that me be that I'm used to the 890lb torque the FL produces) The sound is great. If you give me a holla on AIM-phillipSVT or messenger-phillipsvt@hotmail.com I will let you hear a sound clip of the truck.

 

Didn't expect to get so many response.

Did everyone keep the stock cats or did people change them to high flow cats? How did that work out?

Did anyone just remove the muffler completely? How loud would that be since you still have four cats on it?

Also, my truck is a 2000. When did they start putting on the PI heads and how can I tell if I have them? I've never gotten a clear answer on this question.

 

I kept my stock cats, California is strict w/ air quality! We also kept the 2.5" pipe all the way down. You shouldn't have a problem with a cat back system on a 4.6.
actually improved throttle responce.


Flows 50 series delta 4 chamber.

 

Yesterday I bit the bullit and had a flowmaster installed on my 4.6. I previously had a dynomax super turbo(or thought it was a dynomax). They cut off the old muffler and oh my god it was a monster, and it wasnt a dynomax it looked like some cheap *** pep boys muffler.
Anyways I love the 40 series!! Its got a deep aggresive tone that is not overbearing and doesnt give you a headache. I had the exhaust routed out the side in the stock 97 side exit location with a 3 1/2 in tip.
Love it!!!!!!!!!!!1

 

I just put that dual system (through single muffler) on my 98 scab 4x4 with 4.6 l. The truck was constantly kicking down when traveling in the low 70mph speeds every time you hit a hill or had a head wind. The new system seems to have done the trick as the truck hardly kicks down at all. Only other upgrade on the truck is a K&N filter. I went with the low noise system--it's louder than stock but not so loud you can't hear the radio.

 

flowmaster 3" in dual 21/2' out with three inch tips..the flow is for a 350 chevy(sorry guys)...not much lose on the low end but you get up in the upper RPM pretty quick...and it sure makes people look when you nail it

 

I've had a true dual glasspack with 2 1/4" pipes system for a couple of years now and like it well enough. I do have a slight flat spot from about 1500rpm up to 2500rpms, but other than that it's been great. It still breaks the tires loose if you jump on it from a stop, so if it lost any low end it wasn't much.
The sound is everything I'd ever want from a performance exhaust. Nice low mean rumble when driving at low speeds, and not too loud cruising. Of course my stereo system does have enough power to drown out any noise No raspy popping noise when you jump on it, kind of just roars like a muscle car from the 70's. I guess that's the sound I like?,,,,98

Still want to switch to Magnaflows though, maybe next year?

 

WLF

If you are still watching this thread, how did you hang the pipes from the muffler back and do you have pictures. I am sold on Mangnaflow, especially after your article.