No, there is no power increase and people say that on a dyno 5" actually costs a few horses. What happens on most trucks is you loose actuall exhaust volume. The exhaust looses volume causing it to supposedly swirl more in the piping, where 4" keeps up a higher volume through the piping. Now, if you are making like 600HP and on up, you are making plenty enough volume out of the engine to completely cancel all of that out.imp: The thing with 5" is it just flat sounds so good. I wouldn't give it up for a second, even if it costs me a pair of ponies or three.
Yeah you wouldn't notice a difference in power either way... hey Bobby, what is the cabin noise like w/ your 5" MBRP system? The reason I like the flowmaster is because it is fairly quiet in the cabin but good and loud outside.
pulse phenomenon I don't understand all I know about this, but there is something about the size of the exhaust that causes it to "pulse" if you get the right size. IOW, it actually works with the engine to pull the exhaust out of the manifold instead of just allowing it to pass. If you go too big, you loose this effect. On the other hand....realistically.....unless you are addicted to numbers on the dyno......the real-world difference would probably be negligible, I would suspect. So it comes down to what do you want to spend and what do you want it to sound like. Just my opinion, though.
Thanks guys, kind of what I thought, I think I will keep it 4" but remove the cat and get a better muffler and call it a day. Maybe look into the post turbo down pipe for restriction but thats about it.
Eh, I can make it drive me nuts if I want. Its quieter at WOT than it is at part throttle, with the windows up of course. Reason is, it drones fairly good at 2000-2200 RPM's. About 1/2-5/8 throttle will put the shift points right in that range.:doah: So... either hammer down or go home.rotfl It's not that bad really, just have to keep it out of the drone zone when I am blabbering on the phone, especially with my bluetooth ear piece.:doah:
haha yeah that is what i figured... isnt that 'drone' kindof typical of the strait-through diesel mufflers. Yeah that is why i went for the flowmaster... although i may have sacrificed a few ponies by doing that, i like how it's quieter on the inside
With a flowmaster that has all those chambers, you don't get that sound. Nothing sounds like a strait piped Cummins.
