Howdy! From as much as I've read on this board, I know the factory Y-pipes are very restrictive. I know a catback exhaust system will free up some power, but how will that perform compared to a catback exhaust combined with a freer flowing y-pipe or some other mid pipe? I know that using exhaust tubing that's too big causes a loss of low RPM power, so what is the optimal mid pipe size? I'd like to keep the y-pipe setup and get a catback system, but what are the alternatives to the factory y-pipe? Are there aftermarket y-pipes, or can an exhaust shop bend a custom y-pipe (mandrel bends)?

 

Hi. You need to do some more readin'... and Searchin' ;-))

Follow this thread to answer your questions...

https://www.f150online.com/forums/sh...d.php?t=197816

cheers

 

Ah, thank you! So pretty much, the only option is to use the Magnaflow y-pipe adapter and have a "custom" y-pipe bent for you at a muffler shop? Do they ususally mandrel bend custom pipes, or use the regular pipe benders? Even though ANYTHING is better than the factory y-pipe, isn't mandrel bent pipe better than regular bent pipe for this? Does it really make that much of a difference? Thanks in advance!

 

Since the inlet size of the Magnaflow y-pipe adapter is 2.5", I'm assuming the optimal y-pipe size is 2.5", correct? Will anything bigger cause a loss of torque, and anything smaller be restrictive?

 

mandrel bend is a marketing tool, dont matter how you bend the pipe long as you do it right dont kink it or anything.

 

Hi.

Actually, it's not. Mandrel bending ensures both the cross-section ( 'roundness') and the diameter is preserved throughout the bend - other bending methods don't do that - they either ovalize the bend, rib/crimp it or stretch the metal which reduces the diameter. The best aftermarket catback pipes have constant diameter tubes and non-invasive slip joints.

It's important because anything that changes the flow characteristics will change the velocity of the gas in a negative way ( I think the term used is laminar flow --- explained here: http://www.exploratorium.edu/xref/ph...inar_flow.html ).

Am I being picky? Yup.

Cpaggie: for a stock truck the 2.5 in/ 2.5 out for the stock exhaust, or a 3" out for a 3" catback is what's usually recommended. The muffler shop needs only to supply a short length of 2.5" bent 90 degrees to channel the left pipe into the Y; the right one is a straight shot with perhaps a small 2.5" extension.

 

I put a flowmaster y-pipe on my truck when I put on my Gibson exhaust. It has dual 2.5" inlets and a single 3.5" outlet. It is much more free flowing than the stock y-pipe. However, I am just about to take that setup off and put on a new system that incorporates the x-pipe in the muffler, so a true dual-in, dual-out system. I am just slapping on the Harley edition Magnaflow catback that will replace everything from my y-pipe back.

 

I did some research on this site (wow, the search function works!) and I know I definitely want to upgrade my exhaust. So here's what I'm thinking about:
1) Replace factory Y-pipe with 2.5" in / 3.0" out Y-pipe adapter and new 2.5" pipes.
2) Dynomax SI/SO catback (super turbo, but I'll probably cut out the muffler sooner or later and get the ultraflow muffler welded in).

But I still have a question, should I:
1) remove the 4 factory cats and replace them with 2 high flow cats on the y-pipe
OR
2) just replace everything after the cats (keep the 4 factory cats)?

Or how about just cut off a cat from each side and keep two factory cats (one on each side)?

 

Wow... I've just spent a while reading old posts... I'm really damn confused now on what the best exhaust is. The exhaust I want will:

1) Be louder than stock (not Flowmaster 40 loud though)
2) Have NO LOSS of low RPM power (I rarely ever drive above 2500 RPM)
3) Hopefully offer some better fuel efficiency

I'm wondering if a 3'' SI/SO catback setup is even favorable. Should I just cut out the factory muffler and replace it with something else?

But I definitely realize the factory Y-pipe is a problem, so I plan to use the Magnaflow 2.5" in / ?? " out adapter and build a better y-pipe. Should I stick with the factory 2.5" pipes or get a 3.0" pipe for after the y-pipe?

Also, I don't think I'm going to screw with any of the cats. I just want to work with the y-pipe and everything after that.

 

cpaggie,

from what I can figure out on here, it sounds like you'd be really happy with a magnaflow stainless catback system. The SI/SO 3" is the best way to go on these trucks for flowing and gaining slight power in torque/horsepower. Magnaflow makes a quality product, with a good sound, and it's not too loud. So you could probably buy a magnaflow y pipe too. I won't be buying magnaflow because I want mine louder than that. I like flowmaster loud sound, but deep growly. I'm not sure either what to get, still trying to figure it out since everyone posts differently. I'd also consider banks monster exhaust maybe if I were you, but it's supposed to be louder than magnaflow. I think it is a high quality system too, SI/SO, and is about the same price as magnaflow.

 

I think I've realized that. I'm going to save some money and do my exhaust correctly the first time. I hate nothing more than having to fix a poorly done job. Anyway, since the Magnaflow system is stainless, I'm going to go with the 3" SI/SO Catback setup and use the Magnaflow 2.5" dual in / 3.0" single out Y-pipe adapter and have a muffler shop weld up the new Y-pipe. It'll probably cost about $500-$600, but it'll be peace of mind to know that most of it is stainless steel and I'll never have to worry about failure due to rust and corrosion. I don't think it'll be too free flowing as to kill my low RPM power either. If it does, I'll be pissed!