I've read again and again how the new 600 has a 4" pipe and the 555HO had 3.5"... Has anybody else put a tape measure or caliper on the pipe of there HO? I checked mine (to see what size pipe to use when cutting off the muffler ) and found 12 5/8" circumfrence with the tape, and just to be sure I dug out my calipers and got 4.030" the whole way back from the turbo to the tip.
It also looks to be mandrel bent, so why in the world are people buying the 4" aftermarket setups???????
I have seen a tempting 5" pipe out there, but I think cutting out the muffler should be ALOT cheaper, and just as good for a few extra ponies.
I ordered my truck 9-9-03 and it had 3 miles on it when I picked it up the same day the dealer got it in October.

 

BDude555,

The pipe from the turbo to the muffler is 3 1/2 inch. Then after the muffler 4 inch. The main reason to replace the system, I think, is the stock muffler. But I figured I'd go the whole route and get 4 inch all the way, with stainless and a free flowing muffler.
Really though, with sensible driving and a stock engine the stock system seems good. The main thing I've noticed is a much better sound. The new system takes up less room, is lighter and, probably, more corrosion resistant. Did I mention the MUCH better sound?

Wetspirit

 

Would my truck really benefit from doing a 4" exhaust all the way vs. just doing a high-flow muffler? These exhaust systems are expensive and I don't wanna buy one unless I know I'll really feel a power increase. I agree with changing out the muffler, but would going to a 4" system really do anything other than reduce egt's?

 

Fortunately for you and me, the 2004 HO has the 4" turbo exit flange. Our stock downpipe necks down to 3.5"

I just ordered a 5" straight pipe system that bolts right up at 4" to the turbo and necks up to 5" down below.... and 5" all the way to the end

 

What setup did you go with hoot? Did it replace the cast elbow that sits between the turbo and exhaust?

 

Bought from a fellow named Rip Rook. It does not replace the cast elbow as far as i know.

 

Schorb,

Don't expect to really feel a power increase. Especially from just changing the pipe size. If you are going all out for power, and doing all the other mods, you may need the bigger pipe. But with a stock engine I can't imagne you'll notice any difference.

Hoot,

Why stop at 5"? How much power are you planning on? I heard a rumer that a 9" would be out soon. I'm holding out for a 12"

Wetspirit

 

I have heard that going to a 4"exhaust may not result in true increase in horsepower. That the engine mgmt system is set for the 3.5" and that the engine can actually de-fuel and result in a 10-15 hp loss. That for true gains intake, exhaust, and a chip is what is needed. There is a tread in the TDR forum by some informed people explain the phenomenom.

Mike

 

I've never heard you could lose power by opening up the exhaust!? The only thing I plan on doing performance wise is an AFE ProGuard 7 Intake Kit (already done), exhaust, chip after the 100,000 mile warranty is up and then maybe injectors. That's all I was planning on doing. Now whether the 4" full exhaust will benefit me or not, I don't know. If not, I'll just replace the muffler. All arrows point that the factory muffler is very restrictive.
Money wise, I'd like to only replace the muffler, that's why I was wondering if I would benefit going to a larger exhaust?

 

City muffler and Performance can get you a muffler and piece of pipe to your door for around $100. If I remember right he said it only necked down right before the muffler. I only did a muff replacement on mine since it is 4" all the way. Did not get one from him, but my friends have and they sound good.

 

Mike,

I saw that to. It was enlightening. I need to think things out before upgrading.

Pete

 

5" is a nice looking dia... actually not as big as you think. Even the 6" tip shrinks after extensive use

 

I think mine is 3.5 inches from turbo to muffler. Not only that, but I think the elbow that sits between the turbo and muffler has an inside diameter smaller than 3.5".
Who is City Muffler and Performance? Do they have a web site?

 

I'm sorry, the ebow that sits between the turbo and exhaust pipe, not turbo and muffler...

 

I'm running the Jacobs exhaust brake. Does anyone know the inlet and outlet sizes on the Jacobs elbow?