KYFordFreak: Lets start here in a new thread.

The last time we were talking about replacing the factory cr*p y-pipe with a flowmaster one and you mentioned flowmaster mufflers were hyped up too much.

I will agree with your assumption about flowmaster.

I was just pointing out their dual-out rear sides exhaust system as an alternative to what you were looking for.

I think the flowmaster y-pipe with dual 2.5inch in and single 3inch out is an ideal setup simply because you have two 2.5inch pipes converging into one. If there are out-of-sync exhaust pulses coming through the new y-pipe, theoretically the larger 3inch exit makes for a larger area for those pulses to mix and be on their way out the back.

I'm using a 3" SI/SO Dynomax Ultraflo welded #17220 that I got used from user Raoul_d last week.

A few people have said that it's best to stick with 2.5inch pipe for the system in order not to lose any low rpm torque. While that may be disputed, even if you run dual 2 1/4 pipes it is more flow area than a single 3" system. So I'm not sure how that would figure into the torque equation.

Theoretically, I think the best setup would be a new y-pipe (doesn't have to be flowmaster but their pipe design looks clean) with a 3inch outlet, run a 3" SI muffler. If you really want to keep the torque at low rpm you can always use a 3inch to 2.5inch smooth transition reducer after the muffler and keep your factory 2.5inch rear tailpipe.

For me, I'm not worried and will try the flowmaster universal rear tailpipe in 3inch size. I have only chosen a flowmaster piece here because lots of places carry them and it's half price of the dynomax piece. I couldn't care less about not having a shiny tip on the end like the dynomax pipe... well... I don't think the tip is worth $100 bucks.

I haven't looked into the cost of any other rear tailpipe sections such as magnaflow or anyone else. Perhaps someone could give some suggestions for other manufacturers?

I used some steel wool on that used Ultraflo muffler, cleaned it with BrakeKleen, then I sprayed on some high temperature aluminum paint. Looks like new again. That paint is supposed to be good for 1200 deg.F and it says on the can it will darken at 1000 deg.F . Shouldn't get that hot anyhow under normal use. Ya... I know, they rust from the inside. Looks good though.

The Gibson swept back system is 3inch all the way and they advertise torque so 3inch can't be all bad. I suppose it depends on your muffler and the ultraflo isn't exactly restrictive (straight through).

Now... if you are using a DI/DO muffler then I don't think there's really any point to putting in a y-pipe. You might as well run the right cat into one pipe, and the left bank into the other muffler pipe. I think the air volume of the muffler would act as a good chamber to merge the "flow". Then use DO or SO or whatever you want behind that.

 

Whats the deal with the air box mod.? never saw that one before? how well does it work, does it work? how do you clean your engine with your filter out like that? does it REALLY make a difference? or just look cool? sorry to interrupt your thread i tried to get ahold of you but you didnt see it i guess.

 

p-ferlow
Thanks man, for the starting this and all the info so far. Almost every truck guy I talk to has a different opinion on what sound's good, looks the best, and what size to go with. I have no problem's with Flowmaster. I have not seen or checked out that Flowmaster Thunder system yet.
As for my truck I know I would like to have duals but can't afford nor want to loose little if any low end. I guess it doesn't matter if it's true duals or a split type(catback type) system. I talked at length today with an old friend that drives a newer Chevy 4.8L. He went from a stock single 2 1/2 to a y-piped out straight system. While it did sound good he admidt to me he and another guy we know did loose low end and his best guess was lack of back pressure and we both know Chevy eninges are not great on the bottom end anyhow. He asked me and we talked about adding some type of butterfly valve that could open with throttle acceleration. We both came to the conclusion that it at least would be unquie and it might work but had no idea how to actually control it. This was just a hair brained idea we had but he did like the setup I told him Flatsman had. It's the one with his new x-pipe setup with the interchangeable restictor plates in the tips.
I have no clue exactly what I am going to do with mine yet. I will be studying exhausts a lot and will let you know what I find. I had a pipe size comparison chart for you but the link no longer works, it was in dynomax's tech section.
I guess we are both trying to achieve the best setup that meets our strict needs with the least amount of cost and hassle.

On another note I was almost killed today by a idiot loosing a Bobcat attachment off his trailer. I posted a big message in the general forum. I am still pissed at this guys disrespect.

 

pgh_medic: for FREE, the airbox mod works. I noticed improved throttle response. Other than that it does add some intake noise but it's the kind of noise that sounds like an exhaust tone so it's most welcome in my books. It also seems to hold higher gears longer before requiring a downshift which in my books means slightly increased torque output. It was definitely worth doing in my books. The fipk kits probably flow a tiny fraction more, but is it worth $200 bucks?

The second mod to the airbox is the 90 degree plastic bend between the MAF and the throttle body. Apparently there is a 2 or 2 1/2inch diameter plastic pipe inside it that can be cut out so that you are using the exterior plastic body of this piece to flow air instead of the smaller tube that runs through it. Personally I decided against this mod for the reason that the pipe inside that elbow is smooth and no smaller diameter than the throttle body itself. As well, I think removing it increases air turbulence through the elbow. I didn't think there was any gain from that mod plus it's a bit of a complex operation to get it right with a dremel and all.

Complete instructions are here on my site: http://members.shaw.ca/pferlow/airbox_mod.htm

When you clean the engine compartment just get a plastic bag and pull it over the air filter. Or alternatively remove the k&n element, then pop a plastic bag over the maf.

KYFordFreak: I've seen those butterfly valves before. For the guys that like to run "open" exhaust at the racetrack. Usually they use a wire actuated system like v-brakes on a bicycle with a spring return or something. I suppose if you got creative you could run a vacuum motor that closes the valve at part throttle (higher vacuum) and opens the valve at full throttle (low vacuum). Or try to build something rpm controlled.

If anything, Flowmasters can't be all bad, if you use 3" pipe or one of their DO mufflers you'll probably still keep your torque as Flowmasters are usually slightly more restrictive than other hi-flow mufflers.

I really like the idea and theory behind the spintech mufflers also but pricey.

In any case these discussions are interesting. I've learned a bit here and there.

Oh, I wanted to mention I have the FOU computer code in my 98'. Apparently this is supposedly more aggressive. Any experts on the subject?

 

KYFordFreak: Here's an install video of the Flowmaster ForceII dual out rear system #17222. http://www.flowmastermufflers.com/web10/vids9.html

Here's a picture of it:


If I were to go with such a system I'd go with the #17226 so your towed trailer stays clear of exhaust fumes.


The 50series SUV muffler is probably too quiet though. Better to use a 50series Deltaflow I guess.

 

I thought I'd cut'n'paste this about h-pipes from user Creole0323:

Just installed H-Pipe
I've got a 02 F-150 4x4 FX4 with the 5.4L and I had true duals installed at about 200 miles. My previous truck was a 99 with the 4.6L and on that truck, I also had true duals with no mufflers. I really liked the way the 99 sounded, so I did the 2002 the same way (no muffs).

Actually, I had a Flowmaster 40 series installed on the 2002, but had the muffler shop jerk it out the next day because it was just too quiet.

My current exhaust system is (was) true duals with 2.25 pipe all the way out. I have 4"x18" tips exiting behind each rear wheel facing slightly rearward and downward. The truck sounds great! It's not as loud as you would think unless you get on it pretty good while the truck is still cold.

My only problem is that I felt I lost some low end torque. I've not been too concerned because usually the heaviest thing I pull is a 5x13 foot trailer with 2 fairly heavy ATVs.

Last week I posted a message and read a lot of posts on these scavenger pipes (h and x-pipes). I visited quite a few websites and checked out what they had to say. I came to the conclusion that I just needed to check it out for myself. I decided to get an h-pipe installed just rearward of where the drivers side crosses over and makes it's run to the back of the truck. The pipes are only 4 or so inches apart, so my "H" is very short.

So, basically, here is my conclusion, opinion, yada, yada on the h-pipe on my 5.4.

The exhaust is now a little bit (very little bit) quieter, but maybe a fraction deeper. The new pipe seems to have eliminated most of the rattling when you get on the truck while it's still cold. It has a different tone altogether to it, but just slightly. I really don't know if I like the new sound better or not. It's just that close.

And of course, the reason I actually had it put in...torque...

Well, if my torque increased any at all, it was just slightly. I pulled a small trailer Saturday, but with as little weight as I had on it, I really couldn't tell any difference.

I hope this helps those of you who are considering upgrading your factory exhaust.

Creole

P.S. I've gotta get a digital cam so I get some shots of my truck.

2002 White F-150 4x4 FX4 Supercab
Black Warn Transformer kit
Warn XD9000i winch
KC 150 watt sealed beam Daylighters
Black stepbars
K&N drop in
Stampede low profile bug shield
Vent shade window thingies

waiting on hunting season to get here to get my mud tires

wanting a chip...any recommendations...???

 

Then of course there is always the NO-Y solution. Just take a Manaflow 3" SI / 2.5" DO and mount it backwards where the Y-pipe used to be. Now you have a single 3" pipe out and don't have to pay for a Y-pipe. Works and sounds great!

 

Had the Flowmaster "Y" installed and lost low end torque. Right now, I'm using a Ravin Z-55 with 3" in dual 2 1/2" out, which is too loud. I'm going to a Magnaflow Stainless # 14278, which has 2 1/4" outlets. I'll report the results.

 

Thanks doorslammer, I had heard before that the Flowmaster Y does cause a torque lost.
Why is it so hard to get a good sounding exhaust on these trucks without loosing low end? You would think a Flowmaster Y would help but it doesn't, you would think a x-pipe would really help, except the opposite is true. I guess each one has it's reasons why it doesn't work as well as stock. The Flowmaster Y is too large and the x-pipe is not in an equal length system.
Maybe we are trying to hard and over doing this exhaust thing. Maybe those that have just replaced the muffler and tail pipes (catback) are the smart ones.

 

sorry...double post... below

 

I bet if you go with the flowmaster y-pipe, muffler of your choice (3inch in) and keep your OE tailpipe for the torque restriction you'd be ahead for both torque & horsepower.

The OE Y is a POS. I'd even like to see the difference if someone has just replaced the Y-pipe on it's own, leaving everything else OE.

Sure, I agree if you have a dual-in muffler you can eliminate the y-pipe altogether and have dual 2.5 IN using the muffler's chamber as a quasi-Y. Would probably have the exact same effect as improving the y-junction.

Perhaps the flowmaster y-pipe offers too much exhaust gas scavenging?

 

p_ferlow

I've since un-installed my H-pipe. It had a tone that I just couldn't get used to. After having it cut out, I haven't noticed any difference in "seat of the pants feel". I even reset my computer just in case, but notta.

The biggest thing I noticed is that with the h-pipe welded in, the exhaust didn't have that popping to it (not as bad) when it was cold.

 

Probably neutralized the popping because the h-pipe was equalizing the pressure before it came out the tailpipe(s).

Sorry to hear you didn't like it. As long as the pants-o-meter feels the same, what's the difference eh?

 

these trucks are very sensitive to pipe size when it comes to low end torque. To get the best of both worlds you would need a variable size pipe to accomodate the different rate of flow bettween low and high rpm ranges.

This is a device that can do that but is kind of hokey with it's cable operation. I have been looking high and low for a simmilar device that I saw before that is like the one above but was vacum actuated and connected to the intake manifold. It would work well in theory but nobody can say for sure unless they actually try it.

If someone finds the vacum actuated version of the piece in the above link please do post it. Thanks in advance. My $.02

 

I was thinking about that... vacuum connected. I've mentioned it before but it should really be rpm dependent and not vacuum. If you floor it at low rpm where you want torque you don't want it to increase the exhaust size (low vacuum), rather keep it shut until say 2500-3000rpm when you enter the HP range.

Sounds neat though.