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bought 03 w/ only mod made s the cat is removed. what gains will be made going going to 4" down tube back vs. adding a good muffler to the 3.5" down tube back. is it worth the money in the long run?
 

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the tubing u have is not mandrel bent a new system would be mandrel bent meaning no constriction in the bends it helps quite a bit
 

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Do it......you won't regret it. The drop in EGT's alone is worth it.
 

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The 4" will provide a egt drop. That makes it worth it to most. But other than egt drop there is no performance gain.

Tyler
MPF

plus it sounds cool too!! :rockin
 

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how much temp egt's wise do you think you will drop
 

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I've been wondering the same. I just had the muffler shop cut my cat and muffler off of my stock 3.5" exhaust and weld a piece of pipe in its place. Is there enough EGT drop difference and any performance or sound gains to be had by putting a 4" system (straight) on in place of the 3.5" straight piped system ??

I could be wrong, being that I don't have much experience with this, but I just can't see there being much difference in a 1/2" of pipe. I could see maybe a little difference in the bending of the pipe (the 4" aftermarket system being smoother and less kinked)......but my stock system doesn't look all that bad to me. Again.....correct me if I'm wrong please because I am very curious myself.

With that being said.....I would love to have a 4" system on my truck based upon the reviews and gains everyone seems to see over stock..... But I can't afford it at the moment......therefore the straight piped 3.5" system for $60.
 

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Quicker Then Brian!
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I've been wondering the same. I just had the muffler shop cut my cat and muffler off of my stock 3.5" exhaust and weld a piece of pipe in its place. Is there enough EGT drop difference and any performance or sound gains to be had by putting a 4" system (straight) on in place of the 3.5" straight piped system ??

I could be wrong, being that I don't have much experience with this, but I just can't see there being much difference in a 1/2" of pipe. I could see maybe a little difference in the bending of the pipe (the 4" aftermarket system being smoother and less kinked)......but my stock system doesn't look all that bad to me. Again.....correct me if I'm wrong please because I am very curious myself.

With that being said.....I would love to have a 4" system on my truck based upon the reviews and gains everyone seems to see over stock..... But I can't afford it at the moment......therefore the straight piped 3.5" system for $60.
i agree...i think the difference is minimal....mt truck runs and sounds excellent with the pipe i have and the factory pipe is already mendrel bent so there are no harsh curves or anything really
 

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Don't know if it's true or not but I've been told a larger system will drop a little low end power but gain more on the top end. There was an article in Diesel Power that showed dyno runs for a stock system and a 4" system and the 4" has less power up to 2200 RPM then shot ahead of the stock system.

That being said, I will still put a 4" system on sometime down the road!
 

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Quicker Then Brian!
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Don't know if it's true or not but I've been told a larger system will drop a little low end power but gain more on the top end. There was an article in Diesel Power that showed dyno runs for a stock system and a 4" system and the 4" has less power up to 2200 RPM then shot ahead of the stock system.

That being said, I will still put a 4" system on sometime down the road!
yea but you gotta remember when they say stock they mean still has the CAT and MUFFLER on it....remove these 2 power robbers and i believe your exhaust will be almost as efficient as a 4in kit.
 

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Here are a couple calculations I made:
The cross sectional area of a 3.5" pipe is 9.6", and the cross sectional area of a 4" pipe is 12.5". Nearly 30% more area/flow.

I don't believe this amounts to a huge difference. If you can remove your cat and muffler, I think that's a pretty good idea on the cheap.

I think I'll buy a 4" system just so I can keep my stock exhaust intact.
 

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I used a 4" on my 06' LBZ and it really made a big difference! I picked up 2 MPG and it sounded great! When you're ready for the exhaust please feel free to call, email or PM me and I'll get you the D-Max forum member price. Happy Holidays! :drink

Kind regards,
 

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i would go with a 5 inch. theres like no backpressure at all and most dealers sell it cheaper than a 4 inch exhaust..... i put a 5 inch down pipe back on my 08 and it cost me 290 bux
 
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