I got a question...I see you eliminated those rubber bushings from the factory exhaust, where other companies choose to keep it. Do you happen to be getting some crazy vibration in the stick shift around 1800rpms? I thought thats why those bushings where their? to absorb vibrations...

Are you talking about the vibration dampers that are attached on the sides of the Y-pipes on the stock and the Stillen exhausts?

Yup...I really have no clue how they work or if its entirely needed but I did notice vibrations without them on...I was just wondering

Another question - was the video clip w/ stock cats?

I think it was mentioned it was with 12" reso's, but I've gone back and skimmed for info on if it was stock cats or not, and didn't catch anything...

None whatsoever!

UPDATED-

Thank you to our newest customer- Crbn_Fbr

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It had the stock cats it. The only mod. whatsoever was the TDX cat back exhaust.

I'm not really clear on them either, but my working assumption is that those dampers have more to do with modifying resonance in the exhaust system for sound purposes, rather than anything to do with felt mechanical vibration.

Hmm...I should take mine off to see what it does, just for experimentation's sake.

I noticed that this exhaust system, like most the aftermarket ones (incl. Stillen), does not contain any flex pipes. What are the consequences of not having the flex pipes? Why would Nissan have put them on the stock exhaust?

It seems like all they do is prevent the whole exhaust from moving when the engine torques.

A very valid question!

The reason why most manufacturers use flex joints is to account for inconsistency in their production pieces. Ex: Nissan makes thousands of 370's in one year. The quality assurance on the exhaust system is probably fair at best and the flex joints allow for slight alignment variance.

We have never used flex joints in our production cat back exhaust systems for a number of reasons. Stainless Steel expands when it gets hot and flex joints will add to it like an accordion. They hinder performance by creating turbulence to the exhaust flow from the inside. They allow the system to sag as well.

We have prototyped all of our exhaust systems correctly from day 1 and do not have fitment issues. Our quality assurance is top notch and second to none. I stand behind that until the day I die! Now in some cases we use flex joints. On some of our turbocharged down pipe applications we use them. We judge each case based upon it's circumstances.

The exhaust system is bolted to the manifolds. Then it is hung in rubber. The rubber is to allow movement as to when the engine torques. See the engine is sitting in rubber motor mounts so when it torques everything bolted to it Will want to move with it. If we solid mounted an exhaust to the frame it would break when the engine torqued.

Here is some food for thought,

This is not our first car. We have over 10 high end cars that we currently have a production exhaust system for. Not one uses flex joints in the cat back. Cracking is not an issue that is common with our products especially our cat back's.

If anyone is deeply concerned about the lack of flex joints and feels they want them, We have a mandrel bender in house, we are they designers and producers of all of our products so we can fulfill any request. If you want the flex joints I will install them at an extra fee to make you feel more comfortable. I am not being sarcastic I am being serious! But, in my honest opinion they are not needed.

I will say once again, it is a valid question...

Thank you, Tony
(818) 882-2788

As long as you're being so open about technical stuff re: exhaust: I assumed part of the reason for the flex joints had to do with reducing resonance from engine vibrations in the back half of the exhaust. This isn't really the case?

I always assumed it was for ease of fitment.

I thought it was for allowing bending in the exhaust under engine load.

It is to an extent.

Cars that have very weak motor mounts have an excessive amount of engine travel when it moves. Ex: a place where they would be needed would be on a car with sloppy motor mounts and very stiff rubber hangers. This will allow the front part of the exhaust to travel easier with the engine when it torques.

Now, this particular car has strong motor mounts and the engine travels very little when it torques. That in combination with the rubber hangers underneath that are not on the stiff side allow the exhaust to travel with the engine. If it was an issue for us believe me, I would put flex joints in. But, you don't see our X Pipes cracking or welds at flanges breaking. Reason being, the exhaust has plenty of travel on these cars to allow it move.

Nah, if that was true, you'd have a broken engine mount. It's a fitment / something to go wrong later, device.

Correct, I see more customers with random exhaust systems that come in with blown out flex joints than just about anything. Most of the time they catch them on the pavement a wear all the way through the mesh.

Hey Tony lets make a exhaust for the FX50S I will buy it as soon as you can ship it

Sounds good. This exhaust is looking more tempting by the minute, especially with the weight savings.

Hope some dyno results come soon too.

Everything is looking on schedule for tomorrow evening. Were are shooting to bang it all out in one trip on one night.

Tony,
Thats the best explained and worded explanation I have ever read about them. Good job!

UPDATED-

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Before and after dyno, I assume?

Also, I know it might be hard to request it, but, could you also do it with FI HFC's (for a third set?)

;)

I know this thread is long and it even took me a minute to find it. This is originally what I wrote in reply #201:

Later this week probably Thursday night. But, we are aiming to get it all done in one shot. In the following order:

1) Stock (Baseline)
2) TDX cat back
3) TDX cat back w/ high flow cats
4) TDX cat back w/ resonated test pipes
5) Possibly- stock cat back w/ high flow cats
6) Possibly- stock cat back w/ resonated test pipes

We will get 3-4 runs with each configuration and take the average of each one. Not low stock and high cat back, that is inaccurate and it is false!

It is a Dynojet and it will be set in SAE all the way through.
The only change we will make will be the component we are testing. I will take video and sound clips as well.

I welded a wideband bung in to the stock exhaust to show all of you what the A/F numbers will be stock. I will also have A/F readings in every other configuration to show you if it leans out and how much.

Stay tuned...

BTW (not that this may make any difference for tonight if you're not set up for it), but our cars have a stock wideband O2 in the manifolds, which should be available data via CAN as well.

that was the post I linked to in my post right above you :icon18:

Off to the DYNO, at the very least I will post some numbers late tonight...

PM sent

:excited:

:happydance:

UPDATE-

Stock: An average taken over 3 runs it made just under 281 RWH/ 241 RWT

Next update coming shortly...

omg we are getting play by play here?!?!?! wow talk about suspence!!!!!!! :excited:

Is the baseline coming later?

Stock = baseline:icon18:

It's a Dynojet so it's not surprise we are seeing 281RWHP baseline vs the 254RWHP baseling that Mike (bullitt) put down on Shariff's DD.

That was the baseline. We are strapping it down with the F.I. TDX cat back and stock cats as we speak...

BTW: Dynojet/SAE

NICE sounds like same exact results from my stock baseline!

http://img4.imageshack.us/img4/9567/370zdyno.jpg

Cant wait, and I actually do have all night to wait for it!

This is the definition of dyno porn. Number junkies rejoice.