[jpsimon]

Wrong.

Originally Posted by dzenno

how come this exhaust doesn't have an x-pipe?? Factory one does and there is a very good reason to have an x-pipe. Speaking to some exhaust specialists they told me that the engine efficiency is impacted if exhaust gases are not flowing uniformly which happens in this exhaust as the 2 pipes are not the same after the place where the x-pipe is to sit...it will cause some cylinders in the engine to work harder than others...supersprint has the x-pipe, ultimate racing has it, not sure about others...

think its very important to have...

others, please chime in your thoughts...x-pipe doesn't affect performance that much (if at all, entire exhaust replacement doesn't have a great impact, let alone x-pipe) and i'm wondering why it wasn't included on these pipes???

well said nick:

Originally Posted by Nick@Autobahn

You are correct..... for naturally aspirated cars. If you search for exhausts for other twin turbo cars such as skylines, supras, audi S4s, etc, nearly ALL aftermarket exhausts do not have X pipes because the turbos do not create the same flow as a naturally aspirated exhaust pulse. Due to this, you will actually GAIN power without using an X-Pipe in a turbo vehicle which should be more notable while running higher boost. Also, the 335 has an H-Pipe stock. Fully divorced piping is key for twin turbo cars.

-Nick

[dzenno]

Nick, can you please post examples of exhausts that don't have an x-pipe like you said for skylines, supras, audi S4s where they are similar setups to ours...meaning, split dual exhaust and not on a single side...i haven't found any...don't get me wrong, just trying to understand it...

Here is what I found Google-ing (note how they even recommend it):

Although X-pipes are essential for race cars, adding this modification to a stock car can be a good idea for many reasons – increased power, fuel economy and less noise inside the vehicle. This type of aftermarket performance part is something you can either purchase or have custom-made for you by a good muffler shop. Installation is simple enough for the at-home pro, and the result will be well worth the effort.

The Evolution of the X-Pipe
To understand the importance of the X-pipe in relation to improved performance and power, you have to know about its roots. The X-pipe is really the offspring of the H-pipe design, which was first conceived in the 1960s by the major American car manufacturing companies at the time. Duel exhaust pipes for V-8-powered vehicles are very noisy, as there is no sound wave cancellation between the 2 separate four-cylinder engines and unconnected exhaust systems. Engineers were looking for a way to cut down on interior noise levels and improve the engine's power. They realized that running a balance tube between the two branches of exhaust pipe would work to broaden the torque curve (thus improving engine performance) and dissipate sound resonance in the exhaust system.

In the 1990s improved technological advancements made it possible to construct an exhaust pipe that, instead of connecting by means of a balance pipe at a severe 90-degree angle, could unify the two branches of pipe to create a flow of exhaust in one direction. Now X-pipes are being manufactured for popular performance cars, usually off-road versions minus catalytic converters, but you can also find them in legal models fully equipped with proper emissions equipment. Performing an X-pipe mod is an option that you should consider.

Why X over H?
It has been proven time and again that the X-pipe design is more efficient than the H-pipe. Various tests have shown that for multiple cylinder engines the X-pipe outperforms H-pipe exhaust systems, especially as rpm increases, providing both better torque and power. Unified exhaust pipes work most efficiently with multiple cylinders because of the scavenging effect. With exhaust X-pipes the almost seamless connection between the two exhaust pipes allows sequential firing cylinders to salvage any spent exhaust gases from the combustion chamber more efficiently and creates more room in the cylinder for a fresh intake of undiluted fuel and air. When you have two exhaust pipes, as the velocity in one header tube increases, the pressure in the adjacent tube is lowered causing the exhaust to be sucked out of that cylinder. X-pipes are simply better at doing the job, especially at higher speeds.

Installing Exhaust X-Pipes
This is a simple mod that almost anyone can perform successfully. Most companies produce exhaust X-pipes that are simple bolt-ons that can be installed in less than an hour using the usual hand tools.

If you own a vehicle that doesn't have an X-pipe available, it is possible to have a custom X-pipe assembled for you. A muffler shop can construct it by taking an X-pipe union and bending up some exhaust tubing until it fits. If you decide to make your own exhaust X-pipe from scratch, so-to-speak, remember to place the X-pipe union as close to the rear of the vehicle as you can to increase the power.

A Brief How-To
To install exhaust X-pipes, first begin by positioning the passenger-side header pipe in place and tightening it before moving on to the next step. Make sure it is secure. Now, fit in the actual X-pipe along with the driver's side header pipe. Remember that the long leg of the X must go toward the front driver's side of the car. Now it's time to fit the pipes of the X into position and loosely attach them to the after-cat system. You might have to adjust how the after-cat is hanging for proper tailpipe positioning and tuck up the X-pipe square. On some vehicles the tranny crossmember has an exhaust hangar - if this is the case you can tack the hardware onto the pipes. Tighten the bolts and tack-weld the junctions at the X. Check everything one more time before removing the X-pipe and welding the full length of the junctions. The assembled unit now needs to be bolted back into position - simple as that.
All in all, with exhaust X-pipes torque and power will increase resulting in fast acceleration, improved fuel economy and a nice quiet ride. The difference is noticeable with the installation of X-pipes on a V-8 engine vehicle - interior noise is reduced considerably because you don't hear the firing impulses of 2 four-cylinder engines, but instead hear the noise of all 8 cylinders blasting out of both pipes at once.

[Nick@aep]

^^^ It should be noted that there is no mentioning of any turbo vehicle whatsoever in that writeup. Its completely different. With turbos, the exhaust flow is more or less chopped up as it passes through the turbo unlike the pulses of exhaust generated by a naturally aspirated V8 or V6 motor. In the case of a naturally aspirated motor such as the E46 M3, E39 M5, etc, etc, an X pipe definitely has its benefits in reducing rasp, equalizing flow, etc. It's simply not necessary for a turbo car. I recall Shiv posting a very concise paragraph on exactly what X pipes are not necessary and if I can find it, I'll certainly quote it.

[Nick@aep]

Heres a quote from Shiv that semi-explains it as well-

Originally Posted by shiv@vishnu

I don't find any discernible difference, soundwise, between an x-pipe and divorced pipe. This is because you don't get the same exhaust pulse tuning effect with turbocharged engines as you would with a NA engine. The turbine "chops" up the exhaust pulses before they even enter the exhaust. With no sound difference, all that matters to me is exhaust restriction/power. And that is where my preference of divorced exhausts comes from.

Shiv

A thread from here that discusses it in fairly good depth-
http://www.e90post.com/forums/showthread.php?t=52373

APS Twin Turbo 350Z Exhaust (No X Pipe)
http://www.airpowersystems.com/350z/monster/exhaust.htm

ASP True Dual Audi S4 Exhaust (No X Pipe, I know its a single side exit, but there arent any X Pipes throughout the system)
http://www.autospeed.us/store.php?cr...on=show_detail

APS Twin Turbo C6 Corvette (No X Pipe even on an american V8 since its a TT)
http://www.airpowersystems.com/corvette/exhaust/exh.htm

Greddy True Dual Exhaust for Twin Turbo 350Z (No X Again)
http://www.envisionelite.com/Exhaust...aust_350Z.html

Hopefully this helps you understand why it isnt necessary. Also, I admit, my original statement about skylines, supras, etc, was a bit flawed because most of those use a dual to single setup, so I just provided some examples of cars that do have a dual exit and 2 turbos. The flow is greatly improved without it, and that is what is important.

[dzenno]

Supras, Skylines et al. all have a non-split exhaust, thanks for clarifying.

Don't get me wrong, I'm just doing my research...by the way, just noticed Milltek also has an x-pipe (more like an h-pipe, but they do have it)

This site that you quoted:

A thread from here that discusses it in fairly good depth-
http://www.e90post.com/forums/showthread.php?t=52373

All it says from a technical standpoint is that x-pipe should be there. There are ppl on the thread that are not exhaust specialists (a vendor) that is just making a comment without proper technical backup which to me is unacceptable.

All the other sites that you mentioned, please review the pics, have completely symmetrical exhaust setups and they would never require use of an x-pipe in their design. Those exhausts are different from what we have on our cars. You'll notice that the x-pipe on our cars is placed right in the spot where the design gets into a non-symmetrical shape.

[Nick@aep]

Thats fine, I'm glad youre doing your research. I think I've done all the explaining I need to do to support why we built it without X pipes. The main reason for X-Pipes from what we gathered as I mentioned was to cut down rasp as it is used for in the E46 M3, etc... but Ours didnt rasp, and the flow is better without it. Not only this, but our exhaust builder has over 20+ years of experience building exhausts for turbo cars. If you'd like to discuss technical aspects of exhausts more, shoot me an email, or an IM because I think we've done a fairly good job of exhausting it here which wasnt the right place for it to begin with.

Originally Posted by dzenno

Supras, Skylines et al. all have a non-split exhaust, thanks for clarifying.

Don't get me wrong, I'm just doing my research...by the way, just noticed Milltek also has an x-pipe (more like an h-pipe, but they do have it)

This site that you quoted:

A thread from here that discusses it in fairly good depth-
http://www.e90post.com/forums/showthread.php?t=52373

All it says from a technical standpoint is that x-pipe should be there. There are ppl on the thread that are not exhaust specialists (a vendor) that is just making a comment without proper technical backup which to me is unacceptable.

All the other sites that you mentioned, please review the pics, have completely symmetrical exhaust setups and they would never require use of an x-pipe in their design. Those exhausts are different from what we have on our cars. You'll notice that the x-pipe on our cars is placed right in the spot where the design gets into a non-symmetrical shape.

[jpsimon]

Originally Posted by Nick@Autobahn

because I think we've done a fairly good job of exhausting it here

heyyyoooo

[dzenno]

Nick,

First off, sorry for jacking your thread. You're right, this wasn't the right thread to discuss this in and I should've created a new thread for this discussion.

I also do believe that you have a good "sounding" exhaust (no rasp) BUT my questions were not about its sound and were more centered around its performance/design/engine efficiency, not sure where we lost direction in our discussion.

In any case, I think I got the info I needed on this topic fairly clear in my head and now know what setup I'll be going with.

Cheers -

[Nick@aep]

Originally Posted by dzenno

Nick,

First off, sorry for jacking your thread. You're right, this wasn't the right thread to discuss this in and I should've created a new thread for this discussion.

I also do believe that you have a good "sounding" exhaust (no rasp) BUT my questions were not about its sound and were more centered around its performance/design/engine efficiency, not sure where we lost direction in our discussion.

In any case, I think I got the info I needed on this topic fairly clear in my head and now know what setup I'll be going with.

Cheers -

I dont think we went off topic. I implied that being that turbo cars do not have individual exhaust pulses like an NA car, an X pipe is being used to control rasp, which we dont have, so we moved onto performance benefits of not using it which is BETTER FLOW. Someone in another thread had a good example... When you take 2 garden hoses and point them diagonally at eachother such as the direction an X pipe would meet, what happens to the water? Turbulence. Turbulence is never good for flow, and on turbo cars... flow matters. Thats the last I'm going to respond about this discussion on X-Pipes... Choose whichever system you feel is best for you.

Btw, we built our system with performance in mind first.... it just happened to sound good with only having that in mind from the start.

[ohsnap]

exhaust looks great, pm sent!

[Nick@aep]

Originally Posted by ohsnap

exhaust looks great, pm sent!

replied!

[Nick@aep]

Back to the top! We have extended the last day to receive special pricing to sunday so there is only a few days left to get the system at the discounted price. Please order online using the links found in the original post!

-Nick

[Kyosho]

bump!

[Kyosho]

bump!

[dzenno]

Nick,

Done a lot more research on x-pipes, 335s specifically and this exhaust (sound/performance). After all the questions I had were answered, I now finally have to say:

Your exhaust rocks!! Definitely the best design out there and it absolutely doesn't need x-pipes

I have placed an order for it just now. Can't wait. All the best!

[Nick@aep]

Originally Posted by dzenno

Nick,

Done a lot more research on x-pipes, 335s specifically and this exhaust (sound/performance). After all the questions I had were answered, I now finally have to say:

Your exhaust rocks!! Definitely the best design out there and it absolutely doesn't need x-pipes

I have placed an order for it just now. Can't wait. All the best!

Thank you! Much appreciated. Your order has been processed and will be shipped with the next group of systems when they finish production.

-Nick

[!Xoible]

i hear cows like ae system with quail eggs. if ur not nick ignore this post... except that it's to the top

[phattbam]

what the freaking chicken???

[Digital.James]

People really need to jump on this. My car sounds so deep and exotic with this exhaust and catless DPs. Doesnt compare to any others!

[Gen_E92]

Originally Posted by Digital.James

People really need to jump on this. My car sounds so deep and exotic with this exhaust and catless DPs. Doesnt compare to any others!

sound clip or ban!!! do you think the RR DP is louder than the UR one?

[Digital.James]

Originally Posted by Gen_E92

sound clip or ban!!! do you think the RR DP is louder than the UR one?

My car sounds a bit different than the UR DP sound clip, but not by much. I do have a bit more mods than jpsimon, so maybe that could be different as well.

The past two weeks has been horrible up here in Seattle, weather wise. When the weather clears up Ill make some vids.

[dzenno]

Nick,
Has my order shipped yet?