After reading other exhaust topics, I thought I'd throw out some questions for your thoughts on my future exhaust. Several people have mentioned they thought the FM40's were too loud. I am planning on going with a two in, two out muffler with the pipes exiting the right side in front of the wheel. I was thinking of the FM40 but wondering if running all the exhaust into the single muffle would increase or decrease the noise level? Anybody have experience with that?
Another thought bouncing around tween my ears; I have a Ford 302 with Mustang headers and I'm wondering if I can buy a Mustang header pipe and x-pipe and go custom from there out? I still have all the OEM F100 crossmembers in place. I'm thinking the only way to know for sure is to get an old pipe and do some fit checks. His anybody done this before?

I'm still in the mulling over stage of exhaust so no firm plans yet, just ideas.
Your comments/opinions?
Thanx....

 

I think you have some great ideas there, however using one muffler with two outlets doesn't sound like it would be beneficial as to allowing the engine to breathe. Kinda defeating the purpose of putting free flowing mufflers on? The system your describing is very similar to the 98 and newer F150. I have a flowmaster on my 98 with one muffler. From the muffler to the short exit before the rear wheel, I went with 3" pipe for a little more bark, and it sounds pretty nice, I also have the original cats on it for smog purposes. I recently changed to the Flowmaster40's on my 56 from having magnaflows. The magnaflows were as quiet as my wife's Nissan and didn't do the truck justice. I love the Flowmasters and the sound I get, especially revving it up. They are much louder, but not so loud to desturb the neighborhood. The only thing I don't care for is the detonation or hum I get in the cab at about 2000 RPM. Since my truck is a darksider more than stock, the mufflers are appropriate for me and I've always been partial to loud exhaust (maybe got this from owning Harley's). Flowmaster makes other model of mufflers that are quieter than the 40's also if that is a concern. Personally, I wouldn't go with two pipes into one muffler, but that's me?

 

I'm not that familiar with the FM design, is it a baffled chamber or glass pack type design? Is the two in-two out muffler separately chambered, or do they dump into a single chamber? Either way tho, I doubt it would cause enough backpressure on a 302 to matter, if single chambered the muffler is acting like a crossover pipe.

 

Good comments. Thanx.
My engine has a mild/moderate build to it so good flow will be helpful but I don't want to get too free and sacrifice any bottom end torque. Also, I believe the FM40 with 2 in and 2 out uses a shared baffled chamber design and is available with various pipe diameters. So pipe diameter should not cause a significant restriction if I size it right. However, as you mentioned the single muffler may create excessive back pressure. Don't know as yet. I also was thinking the shared muffler would act as a crossover but that is more hope than anything else.
The exhaust I am emulating is the F150 Lightning type exhaust. I don't know if the Lightning uses one or two mufflers but ideally I'd have the configuration of a Lightning with the sound of a good Mustang Cobra (non smog).
Just thinking out loud.

 

I had to use the mustang trans crossmember because it has humps in it for x-pipe to fit up into. Also the x-pipe hangs from the trans mount as well. I had to remove the frame crossmember in the bell housing area to fit my 5.0/AOD. Check out my gallery. If none of those pix work, let me know.

 

Cowman -

If you go with the 2-in, 2-out FM, you won't need a crossover pipe. The FM's are loud, though. The tone is awsome. Stay with 2 1/2" dia tubes. The FM have very little back pressure, so sharing two pipes into one will probably add just enough backpressure to give you the low end you are looking for. Sounds like a good plan to me.

Of course, I only had to change my exhaust system 5 times to have an opinion about it.