Kind of stuck between Gibson and Flowmaster right now on what I should put on my truck(I have a '91 f-150 inline six).

I want it to be loud outside of the truck, and loud inside but not as loud as it would be from outside of the truck, coz i go on 3.5 hour trips regularly and a loud exhaust for 3.5 hours would get annoying i'd think. Basically i'm looking for something with a good whoompf while accelerating, a good loudness at idle and a decent tune while cruisin.

I can't decide whether to either get a gibson catback(the split rear exit one), a gibson muffler and get a shop to bend the pipe for me. Or buy a flowmaster muffler and get a shop to bend the pipes for me, coz if I go flowmaster I want to the 40 series and I can't find that in a catback system.

Would it be better to get true duals or dummy's?

Thanks!

 

I did a flowmaster (50 series) si/do at a local muffler shop it only cost me about 165/170 out the door. At highway speeds can't really hear it. They custom bent both tail pipes and put tips on them too.

 

Is it that YOU can't hear it, but people on the outside an? Coz i'd like something that's still able to be heard some on the highway.

 

go with the flowmaster 40 series......the 50 series is what i have and you can't really hear it on the highway.....40 series i know you can!

just say no to gibson, but that is only my opinion

 

IF you want to hear it inside at highway speed go with the 40 series cars around you and you will still hear it.
Paul

 

It is a side dump, in front of the rear wheel.
Like of in the same look as the L ( square tips are std, not round ).

That is just me, this is my 3rd Gibson set ( 1 each on 3 trucks ).

Some are on way, some another. I see alot of Ravin mufflers in the posts as well. Maybe another to check on ( unless you already did and don't like it ).

Does the '91 I-6 have 2 headers output on it ?

My last I-6 was on a '81 F-100 custom, I cannot recall what the underneath looked like, and it maybe a moot point, for the question about DI/DO or SI/DO...

On the '81 I did a si/so with a rear exit, using a Thrush muffler.
Did not sound bad at all and I did not haul people in the back in the cap, nor did I really use the rear slider ( opened it when it was sitting in the parking lot for additional ventalation, not on the road. ). Be careful of how you use the bed / cap / rear slider if you get a rear exit system.

 

I got a gibson swept side...I like it a lot but if I had to do it again, I'd go with magnaflow( i hear they are a little louder). I think you'll notice the best performance increase with the gibson over flowmaster, but I don't know from experience.

 

I don't want it to be really loud on the highway, but just a little.

Not sure if it has one or two headers either.

 

I think you can save some bucks if you go with Flowmaster, but I have to say that I am very happy with my Gibson Supertruck after many many miles.

 

Gibson! Magna flow is a straight through exhaust to my knowledge,so in return you will get no back presure. Not good! You need some back presure or you can throw your HP And Torque out the window. Noise or power it is up to you.

 

i heard at the dyno magnaflow increase hp&tq across the board where all other lost in some area's

 

Just installed the Gibson Super Truck exhaust on my 97 F150 with the 4.6. I love it! Sounds good inside and out.

 

The muffler itself has very little to do with back pressure on our trucks. The size of the pipes and the flow throught the cats has more effect. The magnaflow is a great choice.

 

The I-6 has one header(manifold). I think the Flowmaster 40 has a nice sound to it, but if it's performance you want Gibson is the way to go! The FM 40 is louder than the 50, but I think the 50 would give you a little more backpressure. Thus giving you more torque that the I-6 is well known for. I myself have the Flowmaster 40 si/do with 2-1/4" pipes out the back. And I have no regrets.

 

My old 87 was the 4.9 I6 and I just had a Thrush muffler put on it and left the rest alone. It was CHEAP and had a real good sound. As someone else said here, the I6 has great torque and you don't want to risk messing that up. My 87 was a really good truck and with the 4.11 rear combined with that torque and the granny low on the manual tranny it'd pull a house off it's foundation.