I just had a Flowmaster muffler installed on my 4.6L 2004 STX and it is awesome! It is a two chamber with a single inlet and dual outlets. The dual tailpipes exit under the rear bumper. I has that hollow, purr sound like a Mustang, which is exactly the sound I hoped for. The stock muffler and tailpipe were removed with no cutting by removing a clamp that is just behind the Y pipe, so if I ever decide to sell the truck I can either reinstall it or give it to the next owner if they want it.

 

Thats good news , I want the samething, but was worried about it being too loud. It it still pretty quite in the cab? Do you know which series you have.

 

What matter is that you are happy with it!

Got any pics?

 

mechengr2k2,
Just installed the Flomaster on my 05 Screw and you are right that sound it sweet. It not that loud in the cab, but you can feel the horses rumbling.


https://www.f150online.com/galleries....cfm?gnum=4931

 

It's actually an "new old stock" regular 2 chamber. I was told it is comparable to a 40 series. It is not very loud in the cab at all, but you can hear it. It doesn't drown out the radio or a phone call or a conversation or anything like that. Before you couldn't even hear it but now it sounds like a truck. I don't have any pics right now but I will post some soon.

 

i got the flowmaster40 series and it sounds awesome. it felt as if i lost some power, but i only have a butt-dyno, so i could be mistaken

 

I have the force II Series 50 catback and love the sound!!
barely audible at cruising speeds but you can definately hear when you put the right foot down. I debated on the series 40 or 50 but
am pretty happy with the 50 so far. I didnt really want the interior noise that comes with the 40

 

josh,

is your truck a 5.4 or a 4.6?

Does anyone know if there is much sound difference with a flowmaster 40 series between the 2 engine types? Also, does anyone know much about the super 40 series flowmaster? What's the difference in sound between it and an original 40?