3 inch to 4 inch downpipe?

looking to re do my exhaust, should I do a 3 inch down pipe to 4 inch exhaust?

Currently has intake, Ts 6 chip and 3inch downpipe to 3.5inch exhaust with no muffler
I know all downpipes are 2 pieces but are both pieces always 3inches or do some have larger diameters for the second half? or would that be way to hard to fit?

Gonna be hard to get a 4" down pipe in there without a body lift or extensive work. 3" is fine IMO.

Tymar has a 3" downpipe that expands to 4" below the firewall. I'd go that route.

Give Dale a call. I can get you his number if you'd like.

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Strokersace said:

Tymar has a 3" downpipe that expands to 4" below the firewall. I'd go that route.

Give Dale a call. I can get you his number if you'd like.

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Click to expand...

Is it going to be tricky to fit? Like Magnum above said it could be hard without a body lift, which I do not have nor want, I also thought I read something about having to relocate the transmission dipstick tube by using one off a SD? I could be wrong about that. Either was the exhaust clamp put a hole in my tranny dipstick tube so I am replacing it anyways....

Any idea how much the tymar DP is? If you have his number that would be great, I heard of that downpipe but could never find much info on it.

The top section is 3", then expands to 4" on the bottom. It's a 2 piece design like all other downpipes.

Requires the same firewall clearancing as all other 3" downpipes. Nothing extra that I'm aware.

Magnum was assuming you wanted 4" front the turbo, which isn't needed and takes quite a bit of fab. I know because I've done it. Juice isn't worth the squeeze.

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I have the tymar on my truck, wasn't very hard to install at all. No more than normal

A 4" exhaust is more for sound than performance. A 3" downpipe will support 600hp. On a stock truck there will be no gain going larger.

Yeah I never noticed a difference with the big downpipe and 5 inch. But she sure sounds good. Worth it to me

Using a 3" belled to 4" down pipe is worth it. And a 4" exhaust system with 3" to 4" downpipe does make more horsepower than a 3" exhaust. I have the dyno sheets to prove it. After that, it seems to be just a difference in tone.

The guy (ShortBus) who made 595hp using a 3" downpipe did have the exhaust belled out to a 4" exhaust system.

And just for giggles, the stock muffler is good for 400hp (399.8, to be exact).

How much of a difference did the 3-4 make over the 3?

I had a Banks exhaust system that had a 3" downpipe, larger 3.5" tailpipe and the cat was removed. Banks at that time retained using the factory muffler since they had determined that the muffler was not that restrictive. As I recall, the stock muffler was a 3" (3.5"?) straight through design similar to the 4" performance mufflers. This was good for 399.8hp.

I then replaced it with a 3" downpipe belling out to 4" and with a 4" muffler and tailpipe.

Truck went from 399.8 to 408hp with better torque response throughout the power band than the Banks setup. Both readings on the same DynoJet 248 without load cell.

Yeah the stock muffler squeezed down to 3 inch and then back up to 3.5 part way through it. I wonder if the 3-4 makes any real difference on a completely stock truck?

The 3x4 exhaust setup with muffler is worth about 25 rwhp over a stock exhaust from all of the dyno runs I've seen. Rock stock federal truck only makes 175-180 rwhp.