Believe it or not ,,when I went from the stock tips and Milltek 2.5'' tail pipes out from the muffler to a true 2.75'' set-up it did start to drone then,,but it did only get a little louder all the way around.

 

Hi,

just for getting the facts straight: your link points to a cat that has a price of 120$ and a (current) reduction of 45$ thus having a final price of 75$.
It says "you save 45$", not "it costs 45$".
I'm not sure if this is really the cat that was used, but you should not put more oil into the "false facts fire" than is already there.

From the picture of the catalytic matrix alone you can see that this is no cheap cat in terms of build quality. If it were, it would have only a single helix.

A catalytic converter can go bad if used outside of it specs. The price of the core has nothing to say about it's ability to do the job of catalytic conversion, which by the way is an exothermic reaction creating heat by itself when burning the unused fuel.

A bad cat is either rattling because it became loose (this doesn't mean the catalytic conversion is no longer working nor does it mean the flow is affected significantly) or it just becomes inable to burn the excessive fuel because the matrix surface is contaminated or destroyed, which doesn't mean the flow is affected either.

Obviously this cat has seen some excessive heat. Last time I checked, exausts don't create heat by themselves - except for the cat section of course, depending on the amount of unburnt fuel.

To me it looks like as if this exhaust has been used in excessive dyno runs without enough cooling and probably with too high gas temperatures as a result of (too) lean mixtures. Who knows what went wrong on the dyno - probably it was a story like "we can get there ..... we will make it .... errr....we should see some other results .... and then finally: ooops - the exhaust is gone. Too bad, but they were lucky: 911tuning paid for it.

I have a 911tunig exhaust lying here waiting to be put on which has catalytic converters built in that costs probably more than the importing costs of some Korean built exhaust systems that have a "national product sticker" and I think we would be surprised to know how many are being done there.

To some of you the fact that I have an exhaust from Mark will put me in a certain light of self-justifying my purchase, but wait:

I will make pictures of my install and I already have measurements of the before state of my car and I am pretty sure that the stuff that Mark has put together for me will make me happy and my car faster.

You can then make your comments and judge about the build quality and the used parts.

I will open a seperate thread for my exhaust swapping in order to keep things clean - if possible.

One more thing: it is no secret that straight pipes help making the biggest HP on turbo cars. This is just not for everybody from a loudness point of view and you are lucky that you don't have the environmental constraints in the US that others have.

Regards,
Andreas

 

I thought I would cross post this from another thead, as it sums up my feelings about this subject...

Guys,

Today, I spoke to one of our customers that uses our 3" X-cellerator exhaust. I asked him: "Are you still running our 3" X-cellerator exhaust?" Below is his reply:

Hi John,

You bet I am. I tested your system to 600rwhp on our dyno dynamics and it made no difference to power levels from straight to muffler. I don't know what all the fuss is about in this thread. (He is referring to this thread).

It seems the people that are claiming the X-Flow is not optimum for power all have very large builds and are looking for peak HP numbers, regardless of sound quality or drone. The quote above is from a customer with a 600 wheel HP 996TT that dynoed his car with our SpeedTech 3" X-Flow exhaust and then "straight pipes" and found no difference at all in power.

I am certain that this applies to the majority of people reading this thread. We have taken a lot of time to develop systems for the 996TT that sound great (which is what most people want) and perform great as well. These cars are all about enjoyment and I can tell you that there is no greater enjoyment than hearing your 996TT scream like a 997 GT3! We have done the extensive R&D and on road testing to accomplish this...it takes a lot of time, trial and error and patience to get it perfected. I can tell you from experiece, as we do it all the time, it is very easy to spend a lot of time and money on prototypes that sound like sh.. and then have to be repeatedly re-invented until they are perfected in terms of look and sound...it's not easy work, getting everything to fit right and look right is a real pain and it takes a lot of time.

But the main point I would like to make is that IMO, for the majority of 996TT owners, the X-Flow is the way to go and your power will not be compromised. Going from the resrictive OEM exhaust or a conventional system to our 100 cell X-flow is pure bliss for most owners. I know I am keeping mine on - I've tried all the other designs and would never go back to a conventional, twin can or straight pipe system. The X-Flow is the way to go for the majority or owners, expecially anyone concerned about drone - read our testimonials and see how many 996TT owners love an X-Flow...

 

John as part of your extensive testing do you have any back pressure data you can share with us ?

And yes as I said for basic cars x may not be robbing enough to get rid of it . Once you get up in power it can be worth 60-70whp.

 

No backpressure data, just track times with various systems, road testing and dyno data, such as the data I just posted at the 600WHP level. Enough to make me comfortable with the X-Flow at the power level I am familiar with...which is 500-600 AWHP. A lot of our extensive testing time has been spent refining the sound though tweaking various components and working on perfectfing the fit and finish, as well. We approach it as a total package for the majority of users. There will always be individuals like yourself and Tim pushing the envelope and that is great. That's the stuff I like to read about in magazines :-) or here on 6speed!

 

I'm willing to take a bet that the X design is not the best design. There is NO way the gasses criss/cross in the "X" portion like you think. The only way it becomes some what possible is if the tubing ID becomes so big(2.5+") then it doesn't really matter that much> the gasses are still not criss crossing but, just not slamming into each other creating backpressure. Meaning it will still have backpressure but there will be less as the ID og the exhaust increases.

If the tubing length is equal, there is NO possible way for the X design to have less or equal backpressure than a straight pipe.

The ONLY way to test is back pressure, PERIOD!! Dyno charts, customer "seat of the pants" testimonials and coach bench racing mean nothing..

 

I think exhaust manufacturers should test for back pressure, exhaust temps and sound levels and tuning. It's not that difficult. We did it in 30 minutes. Saying you put it on and it works great and Sounds great at 600 whp isn't really "testing". I made 700whp thru an x and 900whp thru an X and it sounded great lol

I made 640whp thru at old cargraphic - just cause it works doesn't mean it's the best way of doing it.

 

We also did 1/4 mile testing of various sizes, designs and pipe diameters. Trap speeds, which are a good indicator of power, remained consistant between 70mm conventional and 2.5 and 3.0 X designs, so in real world measured use, we found no discerable differences between conventional and X at 500-600 AWHP level. That is not seat of the pants testing and in fact may be better than a bench flow test that may register something on a bench, but not really result in a real world difference. There are many ways to test and we felt comfortable with our mix of testing, including actual track times.

I feel that when you are able to combine good track times with a great sound, you have a good product that is fitting for the majority of users...we just choose to test differently than you would, everybody has their own method...

 

Just like I said in the thread I had made - Not that I'm going to be making my car insane or anything like that, but as an average owner I'd rather give up a little bit of power (if any) and really enjoy the sound of my car for the majority of my use.

Everybody is obsessive to some degree, some just obsess over different details and have different priorities. If an exhaust company wanted to make exhausts that had the most potential, they'd have foot long straight pipes coming right off the turbo. Most people that buy them take them off almost immediately it seems. And as a business owner, not really a lot of profit in a straight pipe that Joe Bagofdonuts can get fabricated locally. Now, designing an exhaust that sounds great, fits great & improves performance? That's the name of the game for most exhaust companies. Guys that are pushing 650+rwhp aren't all that common on the 996 platform outside of the forums.

 

Seams like what you are describing that you are looking for in an exhaust is a Speetech or Marski's exhaust system!

 

Would like to at least try something a little different, and won't mind modifying with different muffler combinations in the future to get it where I'd like it to be. If I spend the money on an off the shelf system, I'm not going to want to touch it. They are great, don't get me wrong, just looking to try something different and avoid the porsche tax

 

What turbo's your customer use??

 

gotta love 6spd - a technical back pressure/ exhaust flow thread turns into a selling market for two vendors that dont even have back pressure data on their exhaust smh

 

I am sorry to say this but in all fairness I have to...
I dont believe anyone, including yourself, was every to concerned with wanting,bringing it up or asking for these numbers Before You/Tim just came up with this test..
Yes EuroPipe gives them and if they are right with the same kind of testing ,,that would be a bench mark..
Now that it is on the table, Maybe we will see where this goes and Hopefully it should help to design better products from all that get involved..

 

wellllll in all fariness that is because Tim and I do not make and sell exhausts to people as our business John. i'm an actuary and tim is a steamfitter, its a hobby for us. if i was selling exhausts I would have backrpressure data, EGT drops, logs, sound DB levels cold/warm/idle/cruising/wot etc and i wouldnt use crappy 75$ cats either.