Like the title says. MBRP 3.5" XP on a 06 Screw FX4 installed last night. Initial thoughts are excellent. Sounds pretty much exactly like the link jesse has on here of his sound file. Deep low big sound. I'll post some pics and sound clips within the next few days. $345 shipped WELL worth it.

 

3.5" seems oversize for the 5.4l. MBRP makes a 4" exhaust for the 6.8l and guys that bought it hated it, plus its way oversize for the engine. MBRP should stick to building diesel systems or else learn to size exhaust right for gassers. They do make a nice looking system though.

 

Ohh a jab compliment. Nice!

No performance lose that I can tell and it sounds outstanding. I doubt a company is just throwing oversized exhaust together without testing.

So what's the difference in having one 3.5" as opposed to having dual 2.5"?

 

None. Post sound clip!

 

Some people think when it comes to exhaust bigger is better. I found out otherwise. MBRPs exhaust for the 6.8l is 4" and way to big and killed low end. MBRP obviously did not do their homework on that exhaust and I suspect their 3.5" F-150 exhaust is the same. Their 2.5" dual setup looks better to me. A single 3" catback is a proven performer on the 5.4l and is a good step up from the stock 2.5" pipe.

A SIDO dual setup is a little different. Usually you run a proper size pipe up to the muffler and split to tailpipes. A little larger tailpipe isn't as bad as having oversize piping in front of the muffler. Ever hear of exhaust velocity?

Sorry to be a kill joy. I just figure I'd add what I did in case someone else considers buying a similar size exhaust. Something to think about.

 

That's why I like dual out mufflers for daily drivers. Really, true duals are unnecessary and only create more weight underneath your truck. A 2.25'' or 2.50'' exhaust system is all that is needed. Ideally, you want no restrictions but you do want correct sized piping. That's why I got large piping for my 300; I figure once my exhaust gasses hit that cat and then the muffler, velocity is done with anyway! Might as well get a deeper tone. My exhaust system is a mess. All of my exhaust velocity is accounted for due to my manifolds. After that, they hit a gutted(I think) cat that runs into a 3'' in / dual out muffler. People will tell the OP his exhaust size is too big, but everyone that runs true duals have more weight and less exhaust velocity. Even if the person who runs true duals only has 2'' piping, he's still putting out the equal of 4'' piping!

 

Here's a quick crappy little sound clip my daughter did with her new $30 camera.

YouTube - F150 MBRP Exhaust Start up Drive off

 

Amazing. What type of muffler did you use? Your truck sounds outstanding. Now you have me curious to how your set up would sound on mine.

Added you on YouTube.

 

Sounds nice, but I agree that it seems over-sized for the engine. Too little back-pressure reduces the velocity. Have you had it up to speed on the highway? Any drone yet in the cab?

 

Nice truck brian! Looks sweet.
Would you have said the same thing had he run true dual two inch pipes? True duals at 2'' per pipe is 4''. A lot of people run this. The OP's is only 3.50''.
I'm not trying to start an argument. I'm just trying to point out the fact his exhaust system isn't any more over kill than every other dual exhaust system you see on the road every day.

I'm unsubscribing to this thread because I can see myself unintentionally hijacking it.

Hope you all had a Merry Christmas!!!!

 

No drone at 70-75. You can barely hear it. You know it's there but barely audible. I had Mag SI/DO on my 97 bronco and it had slight drone and it wasn't as loud as this exhaust. Of course the short wheel base Bronco is a whole nother animal. You're almost sitting on the muffler.

I completely understand what the concerns are of the 3.5" directly from the cat back. But in all honesty I cannot feel any bottom end lose at all. I am running an Edge tuner canned on #2 setting so maybe that has something to do with it. This is all from seat of the pants feel. And no, I have no plans spending bucks on a dyno run. JesseRohr (i think is the name) already did this with the same exhaust except his is a pro series mines an xp. Maybe he'll chime in on the torque loss down low. I just don't feel it.

 

Sounds good. I figured it would sound nice an deep with that larger pipe. The 5.4l produces a very good sound.

You can't mulitply a 2" pipe by 2 and figure its equal to a 4". A 2" ID circle has an Area of 3.142" (3.142 x 2 = 6.284) and a 4" ID circle has an area of 12.566". Not even close to 2" x 2. Area and flow are different however and can vary depending on exhaust configuration and bend quality.

A 2" dia pipe with an air velocity of 10fps will flow 13.1CFM of air and a 4" dia pipe with the same air velocity will flow 52.0CFM of air. You can see the X2 approach does not hold true.

 

Might I suggest a little reasearch on what "backpressure" actually is, then you would see the error of your statement.jd

 

Not quite right on the math....

true 2 inch duals... area of each pipe in square inches is equal to radius squared times pi....which works out to 1 x 3.141593 multiply that by two for the second pipe and you come out with 6.283186 square inches


1 3.5 inch output is 1.75x1.75x3.141593 which comes out to 9.6211286 square inches


So...your single output 3.5 inch pipe has 50% more pipe cross section than 2 2 inch pipes....

 

Man! now you got me reconsidering my true duals, arrgh!!!