Upgraded Downpipe only

[Wed Turner]

Has anyone ever just upgraded the downpipe and not the entire exhaust system on their truck? If so, did you see lower EGT's or any other benefit?

I put an exhaust on our last family hauler and did it wrong making it too loud. If I make things louder in the Excursion at all my wife will probably leave me. I figure there could be an advantage to just changing out the downpipe, but wondered if anyone else had gone this route.

[LIL' MIKE]

Im no TECH but i see it as the EGTs drop due to the increased exhaust flow. If you dont enlarge the entirer exhaust your just creating a funnel.
Hopefully someone smarter then me can back me up on this!

[HeavyAssault]

It will feel like you lost power but the powerband will shift higher in the RPMs. It's worth it to help EGTs so pick your poison. I'd get the MBRP downpipe, if you want to delete the cat the MBRP cat delete pipe will fit right in easily.

[Wed Turner]

I've seen a lot of very scientific studies and commentary about exhausts. Basically saying that as the exhaust moves away from the engine it cools off and becomes more dense and requires less space. They went on to suggest that making the exhaust pipe slightly smaller as it gets further from the engine would actually help maintain good airflow because of the cooling effect. I have seen at least one very respected performance company, Saleen, use this theory on some of their exhaust systems. I'm not sure I completely buy into it though. I understand how it would cool and take up less space, but I don't understand how making the pipe smaller down stream would help maintain peak flow.

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[smokersteve]

If you are keeping your stock exhaust, cat and muffler, I do not see a benefit with getting a bigger down pipe. The down pipe is 3" and 3.5" after the flange.

If you have delete pipes and you want a full 3.5" system. I also dont see as much as a benefit since the DP's go for $120+ If you like the idea of bigger sized exhaust, get a 4" system from Performance truck products. they have them cheap and good quality.

[Karls03]

When you get the larger down pipe, it's going to delete the resonantor, then the fun starts! I run a 3.5 dp and 4" straight pipe, no cat, no muffler, no problem. It's only loud when I stomp on it. I realize you have an Excursion, but I doubt it would be that loud straight piped. My wife likes how my Souper Doody sounds.

[MWilbur516]

The 03's had a smaller (2 3/4") foil wrapped down pipe that sucks. Get a MBRP 3.5" DP and delete the cat and muffler, you'll love it and it won't be much louder than stock at all.