Opinions on custom 4" exhaust

[Mike O.]

OK, like many others here I'm hot for a 4" exhaust system and have been considering both the Kennedy and Banks.

However, today I talked to a custom exhaust shop owner that said he would fab a custom alumanized/steel 4" system from the down-pipe back for only $425 installed! This low price made me suspicious and in questioning his methods he stated that he welds EVERTHING up, including the connection to the down-pipe -- no clamps anywhere. He claims ANY type clamp can ultimately come loose and welding is the only way to go. BTW, he uses a MagnaFlow muffler.

The more I questioned him the more defensive he got, so I left the shop with the opinion that I would pay a little more and stay with the big names in exhausts.

What is your opinion on this guy's offer?

[hdmax(mike)]

Welding the joints is a good thing. Welding the exhaust to the truck would be bad. Most likely he welds the hangers to the truck, then spot welds the exhaust to the hanger. I have seen that done many times. It works good, But, if you want to change something on the exhaust you will have to cut it off.

He is also cutting corners with the alumanized/steel. Stainless is the way to go. alumanized/steel tends to rust, even though it isn`t suppost to.

[mackin]

Mike O.

Welding is good but,there's always a but.....I wouldn't weld to the downpipe to eliminate v clamp......If you have to remove or your dealer has to,how?Your under a 100k warranty....I wouldn't eliminate the bolt flange, ditto on removal but this time the tranny or for any other reason back.......I personal would go with a clamp style and then have some one weld the joints if you deem it necessary....I feel those two joints are needed.....This is why it's so cheap I think......JMO


MAC [img]smile.gif[/img]

[2DAMAX]

I really do like my dynomax exhaust at about 1/2 the cost of those other exhausts ck out pic's also sounds awsome good luck.

[CanadaKev]

Mike,
Magnaflow makes a pretty decent system for the DMax. All stainless. Costs $750US plus install. Very easy install. I'm pretty happy with it and it has a good sound with no in cab resonance.

I'm pretty sure Magnaflow is made by Walker.

I would consider your custom exhaust as long as he uses the existing hanger brackets. Even though its not stainless you can save some serious change$

Kev

[ 08-29-2002: Message edited by: CanadaKev ]</p>

[3TV]

I'm not so sure that stainless steel is necessary with a diesel exhaust system. Exhaust systems rust from the inside out, and with a diesel's exhaust, the inside is covered with a layer of oil and soot within just a few miles. And with exhaust gas temperatures as high as 1400 degrees, there is less water in the exhaust system of a diesel than with a gas engine anyway. So I'm going to go against what others have said, namely, the only reason to get a stainless steel exhaust is so you can be certain you have the best exhaust system available, although it may not be needed.

I will second what was said about the Dynomax 4" exhaust, it sounds great, and flows as good as any exhaust on the market. I had a local shop build me a 4" exhaust, that increases to 4" immediately after the turbo, with a Dynomax straight through muffler, which cost me $500 (installed). It utilizes the stock exhaust hangers, which were cut off of the stock system, and welded onto the new system, so everything is rubber mounted.

3TV

[Riverholic]

I just put the banks system on my truck yesterday and am happy to say that it is great. It has a nice rumble to it at idle and sounds great. At cruising speed it doesn't sound any louder than stock, but when you get on the pedal you know its there. I installed it myself in about 1.25 hours and was impressed by the quality of the system.

[George Gozelski]

Hey 3TV, you said you had a custom 4" exhaust made from the turbo back? How in the world did you get a 4" pipe to fit from the turbo down past the firewall to the undeside of your truck?

[3TV]

U'm, probably because no one told us it wouldn't fit. I checked out the exhaust system while the truck was still on the hoist, and although I could not see the bolt together flange where the exhaust system bolts to the turbo I could reach up and feel it. The exhaust flange that bolts to the turbo is 3 1/2" diameter, and I can feel where it "steps up" to 4" diameter tubing about one inch down from the flange. Clearance looked fairly close between the 4" downpipe and the truck body/frame, but it fits just fine. The tubing is then 4" diameter all the way to the tailpipe. I do not use any sort of tailpipe "tip", as I think they look like those coffee can exhaust tips you see on rice rockets.

I never knew the 4" exhaust systems for the Duramax did not include a 4" downpipe. Is that the case? If it is, then I am even more glad I had this custom system made.

3TV

[DMAXDiva]

3TV:

When I was originally shopping for a new system, I was told by most manufacturers that the turbo-down 4 incher was next to impossible to do, therefore they would not pursue it (Banks included). Dynomax was the only manufacturer I spoke with that indicated that a 4 inch down-pipe was indeed in the works, but don't know if it ever materialized (I spoke with them back in April). When I bought the Banks system in June, the rep told me that they had changed course and would eventually have a 4 inch down-pipe available, but didn't have a projected build date.

[Mike O.]

Thanks to all for their opinions. Much good info, as usual. I am going to think about all the options before deciding (3TV's 4" downpipe is very interesting, indeed).

[walkerkd]

i believe the dynomax system is offerd with a 4" down pipe..

[Jelisfc]

Yes Dynomax has a 4" downpipe. It's listed in the new products section.

[mdrag]

3TV,

QUOTE:

"U'm, probably because no one told us it wouldn't fit. I checked out the exhaust system while the truck was still on the hoist, and although I could not see the bolt together flange where the exhaust system bolts to the turbo I could reach up and feel it."

It sounds like 3TV is describing the flange with the circular clamp that the downpipe attaches to - and this is not the direct attachment point to the turbo. You need some really long, thin arms and fingers to reach the back of the turbo housing from underneath the truck since the turbo is located at the top rear of the engine

If you click on the second link in my sig and look at the 9th and 17th pics in the KD exhaust album, you can see the 4" KD downpipe versus the OEM downpipe in the 9th picture, and the KD 4" downpipe installed with the circular clamp near the center of picture 19. I believe that clamp is what 3TV was describing in his post...

There is a section of exhaust that bolts directly to the turbo exhaust manifold, and then the 'downpipe' in the above pics. A 4" circular pipe will not attach directly to the turbo without major mods to the firewall. I do not recall anyone installing an aftermarket exhaust piece that replaces the section that bolts directly to the turbo...

[YZF1R]

Dito mdrag. I took a look at the Dynomax "New Products" section. To me, this is not a turbo down pipe. This is the pipe that's connected TO the turbo down pipe.

I believe alot of confusion has come of most manufactures calling this pipe a turbo down pipe.

Not that it couldn't be done, but it would be very difficult to do 4" off the turbo with proper clearence for heat sheilding. Then again, it is called a "firewall".

Steve

[3TV]

mdrag, thanks for clarifying this. After looking at the photos of the Kennedy "4 inch downpipe" on your web page, I can see that my custom exhaust system steps up to 4" diameter at the exact same place the Kennedy exhaust in your picture does. The only difference I can see, is that the step up itself appears much smoother and more gradual on my exhaust than on the Kennedy exhaust in your pictures. I doubt that the smoother step up makes any difference.

3TV