how much does it benifit to get an aftermarket down pipe? is it worth it, or is the stock one big enough? just wanting to get the egts down as much as possiable without having to go to some sort of injetion-i.e. water

If you have an Allison, there currently isn't any aftermarket downpipes available.

If there isnt a downpipe available then why is there one on my truck? Dynomax offers a full turbo back system.

He said 'aftermarket' downpipes available.



Pretty much all aftermarket exhaust manufacturers advertise turbo back even though they are only downpipe back. We've seen it many times. Sorry. http://www.dieselplace.com/forum/smileys/Cry.gif

All I know is I def. changed my downpipe to 4 inch on my truck.http://www.dieselplace.com/forum/smileys/Clap.gif

Lets see a pic of the Dynomax downpipe, and your old stock downpipe.

There is NO replacement down pipe available unless someone fabricated their own.

What is a downpipe?

It's the pipe that you can't even get to where it's bolted to the back of the turbo. When they designed it they had tight contraints to work with and ended up with a flattened out cobobulation that no one makes a replacement for.

Make a BS'r out of me http://www.dieselplace.com/forum/smileys/HiHi.gif

Here is a real downpipe.... the one in front. It clamps directly to the back of the turbo and can be done in 30 minutes or less.

http://www.dieselplace.com/forum/uploads/15Z_first1.jpgEdited by: hoot

Rest assured.................... its coming!!





MB

Rest assured.................... its coming!!





MB





If you wanted a non biased trucks opinion, let me know. It would probably work real well with your "cool duals" http://www.dieselplace.com/forum/smileys/Big Smile.gif

Heartbeat, you are way to good to me.


MB

Heartbeat, you are way to good to me.


MB








I try. http://www.dieselplace.com/forum/smileys/HiHi.gif http://www.dieselplace.com/forum/smileys/Thumbs Up.gif http://www.dieselplace.com/forum/smileys/HiHi.gif

when i said down pipe i meant anything other than stock. thats what i thought the definition was?? i already have a 4" exhaust from summit that was advertised as being downpipe back, but its after the downpipe. is there a "pipe" from the turbo to the first clamp-right before it bends to go to the back of the truck- for the d-max. if so how will it lower egts??

Moss, you are correct in your description, there is none available yet, but MBRP just said they are working on it. I know of a guy that built one for his 6 speed.

I know of a guy that built one for his 6 speed.


That why I made sure to say "If you have an Allison".

i of course have the ally--nearly smoked!!

What about this? Is it not "turbo back" as the advert says?


http://www.ttspowersystems.com/exhaust_gmdiesel.htm


I even talked to them about the "turbo back" vs "cat back" (which for my truck apparently means from back of down pipe back) and my understanding was that it *is* a new down pipe and he knew I had an Allison...

It is still not the actual down pipe, it is the pipe that is connected to the downpipe. The downpipe bolts directly to the turbo housing and runs down at an angle to the bottom of the engine and stops where the passenger exhaust manifold is. What everyone else calls the downpipe, which it is acutally just the first piece of the regular exhaust, hooks up to here and goes reward. I hope I didnt confuse anyone.

The downpipe bolts to the rear of the turbo and snakes down behind the engine and stops at a v-clamp flange.


All of the exhaust systems currently for sale, including the one above (which is actually labeled as "turbo down pipe back") start at the v-clamp flange and go from there. This replaces the "cat", or if you buy "cat back" then they leave that piece out of the kit. In either case, the restrictive, flattened factory downpipe is still attached to the turbo.


I spoke to Steve Cole (TTS) at the LA dyno day, and he has an interesting downpipe in development, hopefully it'll be out soon.


I'm also anxious to see what MBRP comes out with, their fully polished stainless systems are a bit pricey, but look like a million bucks. If you're building a super clean street truck or a show truck, it's a must have!


I replaced a CT Sonic pipe on my Yamaha Raptor with an MBRP polished stainless pipe, it turned a nice gold color, I never polish it. I purchased it from Craycraft Racing, in Aledo, TX and they happened to be in Glamis, CA for 4 Stroke Wars II. They showed off their engines and the full line of MBRP exhaust systems.

All of the exhaust systems currently for sale, including the one above (which is actually labeled as "turbo down pipe back") start at the v-clamp flange and go from there.


Actually, if you read the description above the pricing categories, it says "Turbo Back". It goes on to say specifically "replacing the stock 3" down pipe". But thanks for the info.


I guess when I asked him specifically if the down pipe would make any real difference, he was just talking about that front pipe. I know he did talk about the various joints where things tied in and such (which I was not in a position to look at while talking to him) so I'm sure the misunderstanding was mine and not intentional on his part. I was very impressed with his help and customer service. Still, seems the description should/could be a little more clear...


Now I wonder if I should delay my order (which I planned to place next week) till this new "interesting" down pipe option comes available. He previously indicated that the more expensive "down pipe back" system made little to no difference in most situations. I wonder if the down pipe will be worth extra money for those not looking for every last bit of performance and degree of EGT reduction...Edited by: BadDog

Bad Dog, you're right, I agree, it is a bit misleading. Honestly, most ads are even more confusing. Kennedy's exhaust description is clear "from downpipe back" but all of the rest I've seen were borderline deceptive.


As for the original question - would a new downpipe help. Yes, on a high hp truck it would probably help quite a bit with EGTs at the upper end. Even with trucks making 125hp extra or more, I'd *guess* that it would make a worthwhile difference.


Everyone who has looked at the factory downpipe says it's all smashed and restrictive.

The downpipe is smashed but it's got a pretty large cross section.

The factory downpipe is only 2.5 inch i.d. just before the band clamp, which is not even close to large enough. But in my testing I found very minimal gains by changing it. In my opinion most that would change it will eventually change the turbo which will call for a different setup.

IMO All manufacutrers should say " front pipe back" system. When we were setting up our latest catalog we really found it confusing as to what everyone else in the market war really offering. To my knowledge there is not a true downpipe back system on the market......... yet.


MB

I just received my Magnaflow 4" SS system, which was advertised as being "downpipe-back", but now I'm confused as to what they're calling the downpipe.


It starts with the pipe right in front of the muffler which has the 4-bolt flange. Shouldn't it have the pipe which attaches to the other side of that 4-bolt flange and then curves up to what I thought was the "down-pipe"?http://www.dieselplace.com/forum/smileys/Angry.gif

Same as what they call CAT back. Doesn't include the CAT just like "Downpipe Back" doesn't include the downpipe.

It means from the CAT (the end of it) back.

Or from the down pipe (the end of it) back.

I just talked to Magnaflow and their system is actually from the downpipe EXTENSION pipe back, so their advertisement is a bit misleading.


I think the Banks and probably most other higher priced systems include the downpipe extension pipe (the pipe which connects to the downpipe at the C-clamp), but the Magnaflow systems don't. They start at the 4-bolt flange.


I guess it'll make installation easier, but I wonder how much EGTs I'll be losing since only half of the exhaust will be 4".

There are two different downpipes that the factory uses. One is smaller than the other so in makeing comparisions it's hard to do. Our exhaust kits are sold as a Catback which starts at the 4 bolt flange and goes to the exit of the truck, or the Downpipe back which starts at the downpipe and goes to the exit. I think it would be great if everyone used the same terminology but they do not. We use Cat back because the trucks equipped with cats are in the front pipe as some people call it and it's not legal to be removed from any truck used on the highway in the USA. Not sure about the rules north of the border.


What we have found on vehicles with cats is app. 75 -120* drop in EGT's. Vehicles without cats drop app. 100 -150*. Replaceing the front pipe from a factory non cat pipe to a 4" pipe we found no change in EGT's until we were above 400 RwHp. Now if you were to remove the cat and replace it with a 4" pipe you would be able to gain a little more EGT drop, but since we all know this is illegal I'm sure none of you would order the front pipe for a non cat truck and install it on a cat equipped unit.

My 01 does NOT have a CAT, and the Magnaflow system was advertised as "down-pipe" back, but it actually starts at the 4-bolt flange. So I think their advertising is misleading, but since you didn't see any further drop in EGTs on trucks below 400 rwhp, I guess I won't worry about it too much.


Bottom line--- you get what you pay for. My system is stainless and was only ~$400. I don't think the one extra piece is worth $300+ (higher priced systems, i.e. Banks) so I'll just keep what I have as long as the fit is good...http://www.dieselplace.com/forum/smileys/Approve.gif

i bought a summit down pipe back aluminized kit for 300 and it is from the v clamp back!! very cheap sound great to me and my friends

Forgive my ignorance if im wrong but i juts went to the TTS web site and they clamed to have made a true turbo back exaust system for 2001-2004 duramax. they have pics of the exaust and it looks like they rilly did make a new down pipe from what I can tell. Also in the literatur It says and I quoat "replacing the stock 3" down pipe into a 4" stainless steal." Ill call them tomrow and make sure. Everyone pray im righthttp://dieselplace.com/forum/smileys/Big%20Smile.gif. If not, Im deeply sorry for getting your hopes uphttp://dieselplace.com/forum/smileys/Cry.gif. Edited by: Aron420

Aron420


The web site is wrong, sorry. We have made the down pipe but it is not for sale at this time, guess the graphics guy got alittle ahead of us. The kits are showen as a Down pipe back or Cat back. I will get them to fix the text on the site Monday.