Boost

[Randy Stinchcomb]

2015 X-Sport, haven't stuck a Vacuum gauge on it yet but how many PSI iz stock?

This iz my 1st "street car/truck" with Turbos, so boost iz important to make HP/TQ. I sea where they make aftermarket exhaust that are 2.50" vs the factory 2.25", now I know it's Only a 1/4" difference but does engine boost relate to backpressure?
So if by increasing the exhaust pipe diameter promotes better exhaust flow, will it hurt or cut into boost pressure?

Sorry, just trying to justify  $1500.00 or so for exhaust

 

[sholxgt]

Stock boost varies from 10 to 14 psi depending on multiple variables.

There is NO justification for an aftermarket cat back other than sound and bling.  It will not decrease or increase boost.  The ECU has complete control and it will hit targeted torque demanded and use the amount of boost required to do so regardless of exhaust systems.

Downpipes do more than the cat back and still the only real gain is potentially getting into boost sooner.  I have catted PPE downpipes and have no complaints, but the power gain is negligible/possibly zero.  Tune and fuel choice will do more than anything else you can modify.

 

[derfdog15]

As said above, catback will do nothing except add ear candy/eye candy. Downpipes will allow for boost to come in quicker, but will not really be beneficial on the stock tune (negligable benefit).

On an aftermarket tune, however, you will see nice gains with the downpipes as you can increase the boost targets, change how boost comes on, and utilize boost being available at lower RPM. 2.5" downpipes allow for a much better spool than the stock ones.

 

[Randy Stinchcomb]

Ok, so then you can bolt-up the larger 2.5 dp to the 2.25, that makes things more doable, $$$ wise.
Now next question, if I do that, iz there any need to cut in an X pipe into it aft of the cats?

 

[sholxgt]

I'm not familiar with the exhaust on the X-sport, but on my MKS there is a third catalytic converter immediately after the downpipes that acts similar to an x-pipe.  Also, the diameter of the 2.5" downpipes matches the diameter of the piping on the third cat.

I see very little room for improvement over the stock exhaust.  It is fairly large and has acceptable bends.  I'm not surprised by the dyno results that show practically no gain with cat back exhausts for the MKS/SHO, but maybe the X-sport is different?

 

[derfdog15]

2.5" downpipes will bolt up no problem to stock set up.

For the exhaust (on the SHO), stock has a cat on each downpipe, then a third cat on the midpipe portion(dual in dual out) and then the stock resonator (dual in dual out), then goes to the back. Not sure on the explorer sport if its the same, as the SEL taurus with 3.5L and AWD only get dual pipes at the rear and have a single pipe for midpipe, no clue if your explorer is truely dual or not.

Either way, if you want a little more growl, you can cut out the 3rd cat, and resonator, and replace that section with an X pipe. I left my 3rd cat, due to not wanting to tune for it/shop not wanting to cut it out, and it still sounds nice with the resonator replaced with an X pipe, and Summit Race mufflers in place of stock.

But, stock, there should be a resonator (which is basically a muffled X pipe, and the 3rd cat) if you have a true dual setup

 

[hawkeye93]

Explorer Sport has dual exhaust with 2 cats, one on each downpipe.  There is no third cat on the Explorer.

 

[Randy Stinchcomb]

Right, its a true dual exhaust system and the mid pipes run side-by-side for about 4' and looks like the perfect place for a X-over. Well I think it's doable and as stated above the rest of the exhaust iz done well, 2.25 thru out and no sharp bends.
One thing I've noticed about Fords over the last 15 or so years, Ford can build sum pretty good exhaust systems when they want to ie: Shelby, Cobra, GT, Lightning, RS, SHO