I have been considering swapping out my stock exhaust for a 4" aftermarket exhaust (DPPI).

My truck specs are below with the following changes coming in the near future:

- Edge EZ
- Ram Air III
- EGT Gauge

I have been told by a few people that there is no real advantage or reason to remove the stock exhaust and go with the 4" system. As I understand it, the stock pipe is 3.5" from the turbo to the muffler and then 4" from the muffler back.

So, my question is, given my truck and the modifications I plan to make, what will it gain me to install a 4" exhaust? I don't want to do it just to do it. If I'm going to spend the money on it I want there to be a worthwhile benefit.

Thanks for you input.

-Can'twaittofinallybombthistruckHoss

 

Anything that gets rid of the stock (restrictive) muffler is better. There are so many exhuast choices. A lot of people are just cutting out the muffler and replacing it with free flow Donanldson muffler or straight 4 inch pipe. You keep the 3 1/2 downturn from the turbo (about 18 inches) and just remove the rest that goes straight back. This will flow just as good as a 4 inch system. I'm about to straight pipe mine and if I dont like it I will go with a free flow muffler. You will save a bundle of money. Most custom muffler shops wil charge about $60 dollars. A muffler will cost you another $50 - $80. If you do it yourself you will save even more $$. You can buy a complete 4 inch system but you wont be able to tell the difference in power or EGT from the above methods.

 

Deere nut, how come the 3 1/2 downturn doesn't need to be replaced with a 4"

 

For my now broke, budget minded self, If I did it again I'd probably just cut out the muffler.

 

Jmac,
You could replace the downturn if you could get someone to bend you a peiece of 4" pipe. There is no advantage on mild upgrades to change the downturn pipe to 4 inch (especially with straight pipe or free flow muffler). It's hard to find a shop that will bend 4" pipe and the turbo outlet is still 3 1/2 inch so one end of the pipe would still have to be 3 1/2.

 

If I werer doing it all over again, I'd replace just the muffler and put a cool looking tip on the out chute. The rest of the system is overkill and the 2200 rpm drone is killer. Makes your fillings vibrate! Keep the $500 in your pocket, spend the $80 or so for a Donaldson muffler ( or similar ), $50 to install it, and $50 for a tip. You'll be dollars ahead.

I'm doing the exact same stuff to my wife's truck and have the exhaust and a slightly used, but in showroom condition, Scotty III already on. Oh yeah, EZ too. The gauges should get here tomorrow.

 

So, tell me more about this Donaldson muffler. I've heard several people mention them but have not seen them before.

Does anyone make a straight through muffler that will replace the factory muffler? If so, how do they deal with the offset of the pipe?

 

I Went with the Banks DP, 7 feet of 4inch straight pipe, and flowpro muff, and used the stock tail pipe. It was around 300 for the setup installing it myself, and the results were great! BEST OF all....... NO Drone! I'd do it the exact same way if I was to do it again.

Rich

 

So what's the noise, sound difference of these setups? Stock - Donaldson - Banks - etc?

 

Hoss, you can check out the Donaldson mufflers at www.airflo.com. It's a big rig place based out of Portland Or. but they do sell all over the country.

 

Is Flo-Pro that one that has the auger bit looking thing twisted up inside of it??

 

No.... it's a straight through design with very little restriction. It has a very nice quite tone to it unless your in the throttle

 

What's so good about the Donaldson? I've also heard guys talking about the Nelson muffler too. Are there many differences between the two? Are they both free-flowing mufflers? One quieter than the other?

 

I think the Don and Nel muffs are quieter than the Banks, Magnaflow, DPP, etc, yet still flow much better than stock. They're longer than most others and quieter.

That's what I've been able to gather from reading thousands of posts on muffies.

 

I read somewhere that the 04.5 has a 4" turndown and it will fit on the 03 and 04 turbo.

Anybody know if that is trus?