I am just trying to see if there is anyone out there who has ever had a Flowmaster 50 series, been unhappy with it, and changed to the 40 series. I know there are dozens of threads that compare the two, but I just wanted to get opinions from people who have had both(pref. on a 5.4). Thanks.

 

I had a Flowmaster 50 series (3 chamber) in a 94 Chevy K1500 350 TBI. Just as loud as the stock muffler but at a lower tone/rumble.
Now I got a 40 series Delta Flow (two chamber) in my 1999 F250 L.D. 5.4L, and I tell you the sound is awesome. Not loud like straights. I get alot of compliments on the sound. Make sure you do some research about correct pipe size in this forum. It seems Fords are very touchy on backpressure.

 

I had a Flowmaster 50 series (3 chamber) in a 94 Chevy K1500 350 TBI. Just as loud as the stock muffler but at a lower tone/rumble.
Now I got a 40 series Delta Flow (two chamber) in my 1999 F250 L.D. 5.4L, and I tell you the sound is awesome. Not loud like straights. I get alot of compliments on the sound. Make sure you do some research about correct pipe size in this forum. It seems Fords are very touchy on backpressure.

 

How much do they cost?
A ford tech told me that taking the muffler off will not harm the warranty in any way. I told him I wanted to run straight pipes on my Lightning and he said have at it. Now if only I could get a muffler shop to help me out...

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99 Black Lightning
created 8/17/99, bought 9/25/99
#3681/4000
factory tonneau cover
100k mile warrantee, bed/under liner, paint protected
W:L:T ratio
5:2:1

 

I've been there and done that also. There isn't much difference at all-except all the resonance of the 40.I gave my dad my 50 and had identical pipes put on his truck.His 4.6 with the 50 is identical to my 5.4 with the 40 at idle.Accelerating mine is NO louder than his, but his has the deeper tone.The difference comes at about 60-65 mph.The 40 has terrible interior resonance. I imagine the 40 deltaflow would get rid of it. I also had more low rpm power when I had the 50. You can tell a big loss with the 40.I'd recommend the 50 because it's deep sound and creates more torque or try the delta flow 40. I'm currently looking for louder but still deep.Seems impossible with these 4 cats on our trucks.

 

Ford4life:
I did just that. Please read my earlier post:
https://www.f150online.com/f150board...ML/000380.html

I started with a complete kit that had a 50, then swapped the muffler out to a 40 Delta Flow.

[This message has been edited by selva1 (edited 06-15-2000).]