Just doing some "research" as my 300 rebuild is approaching and came accross this. Does it really fill the need for an X-over? Its only $130ish on amazone.
Dynomax® Performance Exhaust | Mufflers | Ultra Flo™ X Mufflers

 

I don't own one but that looks like a good muffler I generally prefer the sound of glass filled mufflers like that, and yes it would do the trick.

That said however you don't need it, your better off with a 6 merging them in to a Y-pipe and large single to the muffler. It's both better sounding, better flowing and fits better under the truck then 2 pipes.

EDIT; What kinda sound ya going for and do you want dual outlets?

 

I did but realized : a six aint a V8. Listened to all the sound clips at the beginning of the Inline 6 forum ( here), and what ever else I could find on youtube. So to answer your question no, duel pipes are not a (want) must have. What I am hoping for is deep and beefy.

 

I'm not a 300 expert, and I'm surprised one hasn't chimed in yet. But I've done a fair amount of exhaust work. And in general the sooner and longer the flows come together the smoother sounding(less sharp tones and more rumble instead) within reason of course. Also the more equal the pipes are between the head and where they merge the smoother the sound.

I would think a early well done Y-pipe to a single 3" "glass pack" out to a single 3" or 2.5" tailpipe would give a real nice rumble. Just my opinion though.

 

Joe, I have a couple Flowmaster 40 series mufflers, if you want we can add that into the package of Clifford stuff you're buying off me. Have some other stuff you may want too. Just call me.

 

"Does it really fill the need for an X-over?"

There is no particular 'need' for an X-pipe or H-pipe on these engines. But, no harm is done using them. Having an 'X' feature built in the muffler eliminates having an external, extra piece in the system if one wants the 'X' feature.

 

Joe is getting a Clifford 2 piece header so that explains his need for either a Y pipe or crossover.

 

It looks like the hot ticket to me. I plan to install one on my big six Attic Anglia project.

 

"...need for either a Y pipe or crossover" There is no particular established 'need' with these engines like there might be for a V8. True duals with no X or H pipes can and are run by some on these engines. Again, no harm done using an X or H pipe...but not particularly necessary.

 

Ok that changes things, the long tube or short version?

2 piece headers are great on these engines as they are naturally 180deg headers. In which case there is a real benefit to keeping the 2 sections separate and as equal length as possible for 2-4'. By keeping them separate the exhaust pulses are more spaced in each pipe allowing one pulses momentum to help better pull the following pulse. After about 4' from the collector this though tends to add a restriction in the 2.5" pipe and the more spaced pulses add to a sharper exhaust tone. This is where keeping them equal length comes into play, if the 2 pipes are exactly equal in length then the 2 sides can come together smoothly and the pulses merge like a zipper. At this is where the simplest and quietest answer is a dual inlet 3" single outlet muffler on out to the tailpipe. But IDK if you guys will believe me but if kept equal bringing the 2 sides together evenly and smoothly will have a real quieting effect possibly making a large muffler unnecessary.

However the super awesome thing for Joe the welder to fab up would be to add a couple of venturis/steps, and a hi flow y-pipe to the system. Using a venturi at the merge points at both collectors and Y-pipe can help speed the gasses and lower pressure at the tail end of each pulse helping in pulling out he next. And stepping to 3' from 2.5' at the tail end of the 2-4' and then to the Y will have a similar effect.



Additionally this is the time to add exhaust crankcase scavenging to replace the effect of the PCV valve at high throttle low vacuum conditions.

 

I had to read that a couple times to understand it. Once I start to build this puppy you guys are going to be tired of me asking questions and calling ya all. I'm close. Just not quite ready to pull the trigger. Hopefully early April, I get an early Xmas.

 

If you're getting rid of some Flowmaster 40's I'm interested. Can you pm me the details? Thanks