[FlukeSS]

Originally Posted by 6spdhyperblue

There is an xpipe. They are not independent. I don’t know what else to tell ya.

There are plenty of pictures if you search here if you don’t believe us. Maybe oldman had a post on it

As I also stated before, according to mishimoto and Phastek the diameter is 2.75" I have a 3" x-pipe. Mishimoto states the pipes are independent and not connected. And I have provided a reference link for this as well.

Either way again basic physics. Wider diameter = more volume of exhaust thus allowing the engine to breath more. A breathing engine produces power.

But telling people an x-pipe does nothing is factually wrong, and has been proven countless times.

As I explained before, what is more likely, I have a unicorn Camaro SS that is 420rwhp with all stock parts (including cat restrictions) when the average Camaro SS baselines between 390-400? Or the X-pipe with a wider diameter does nothing even after a tune, when all the math checks out?

Lets assume for a moment I do have a unicorn SS with 420rwhp with all stock parts, that means the upgrades I did changes the numbers drastically across the board.

Headers: 0 hp gain
CAI: 0 hp gain
X-Pipe: 0 hp gain
E85: 40hp gain

This is what you are saying.

Because if we assume headers add 20-25hp then the math doesn't check out that my car is a unicorn with 419rwhp with all stock parts.

Again, what is more likely?

Headers: 20 hp gain
CAI: 0 hp gain
3" X-Pipe: 0 hp gain
E85: 20 hp gain

Again numbers seem unlikely for E85 when the average gain is 30-35 hp PLENTY of data to support this, and one claim I saw on youtube of 50 rwhp gain. (no I don't believe that claim) But also the fact my CAI was tested to provide up to 9hp with a tune.

That basically means my car would have to have baselined for 410 rwhp which is far more common than 420 rwhp, but far less common than the average of 390-400.

Statistics and probability. Like I said before I don't have a baseline number for you so pick your poison, but when the math doesn't add up then realistically the statement is false, such as the E85 example above.

There is no way you can explain an 85hp gain at the crank over stock by just headers and E85 unless my Tuner makes Pray look stupid by comparison. He does have a PHD in physics after all?

The only comment my tuner said about my setup is that I had a "mean" intake. Now truthfully I don't know what that means specifically. But I take it to mean that my engine is breathing the way it is supposed to.

[6spdhyperblue]

I never said anything about diameter other than the afm valves choking down to almost 2.5”

Did you read that article?

[FlukeSS]

To be fair, I will admit one thing ALMN said that would account for the math.

Removing restrictions such as my cat delete with my headers.

I'm not sure to be honest. I can't find any sort of test to confirm nor deny this.

That would change the numbers to be more like this:

Headers: 28 hp (inclusive of cat delete)
CAI: 0 hp
X-Pipe: 0 hp
E85: 31 hp (According to my dyno sheet I gained 31hp here)

Which again means my car baselined at 400 rwhp.

[FlukeSS]

Originally Posted by 6spdhyperblue

I never said anything about diameter other than the afm valves choking down to almost 2.5”

Did you read that article?

You didn't say it, but ALMN did.

And he said nothing when I told him my X-Pipe is 3" diameter and not the stock 2.75"

There is a gain to be had there, how much on my car obviously I won't know without a true baseline, but we can make assumptions about my baseline based on the amount of power gained over stock at the crank assuming of course GM is accurate that our cars are in fact 455 hp at the crank.

The parasitic loss from 459 to 540 at the crank comes to 15%. If we assume my baseline is 400 rwhp and the car is 455 at the crank then the parasitic loss comes to 13.9%.

Still think my car is a unicorn with 420 rwhp? That comes to an 8.7% parasitic loss.

[LT4Greg]

If a owner wants to add the X-pipe then I see no reasons not too. It’s their money. I was even thinking of adding one to my ZL1 in the future.

[enzia35]

I regret doing so now at this point in time. No performance improvement since I didn’t delete any cats, and about to trade the car.

[ALMN]

Originally Posted by enzia35

I regret doing so now at this point in time. No performance improvement since I didn’t delete any cats, and about to trade the car.

I had the same experience in my previous cars. Back then a full catback Corsa system cost little over a grand now looking at their website, $2,300 for an NPP axle back plus $800 for an x pipe is too much waste of money. If you look at the ZL1 exhaust for example, identical to an ss npp exhaust, a 2.75” diameter with the only difference being little larger exhaust tips. That is for a forced induced 650 hp/ torque camaro. Chevy did their homework and if people want actual gains I recommend dropping the cats or switching to high flow cats. Stock exhaust is good enough and doesn’t have much restriction. I would rather drop $3,000 as part of a head/cam intake manifold or a supercharger setup rather than a catback or axleback exhaust.

Same goes for so called cold air intakes. Drop a big mouth snorkel with K&N drop in filter and get a tune. No need to spend so much money on intakes.

[KingLT1]

6sspdhyperblue is correct. factory exhaust is equipped with an X pipe. Auto cars will see a little gain from removing the afm valve section. The gains would be larger on a setup making a lot more power.

The biggest gain for the dollar spent on a stock car is a flex fuel sensor and tune, followed by a trans tune, and then cat delete and/or headers. after that diminishing returns on investment starts to creep up. I am referring to gains on the track or street verified with a dragy. I don't give a damn what the dyno reads. Dynos are a tool to make tuning easier...nothing more. Without a actual baseline it's all ricer math.

[FlukeSS]

Originally Posted by KingLT1

6sspdhyperblue is correct. factory exhaust is equipped with an X pipe. Auto cars will see a little gain from removing the afm valve section. The gains would be larger on a setup making a lot more power.

The biggest gain for the dollar spent on a stock car is a flex fuel sensor and tune, followed by a trans tune, and then cat delete and/or headers. after that diminishing returns on investment starts to creep up. I am referring to gains on the track or street verified with a dragy. I don't give a damn what the dyno reads. Dynos are a tool to make tuning easier...nothing more. Without a actual baseline it's all ricer math.

Fair enough King, but you also confirmed what I said as well.

People should not be telling everyone an X-Pipe doesn't provide gains.

The fact is they do, under certain conditions, which my car meets some of those conditions because of the headers and cat delete. I didn't just randomly pick parts because I'm a cheap SOB. I chose the parts for a reason to build for longer term goals. As I stated before as well I did a ton of research on the parts I have before I commit to buying them. As much as months of research, reading, reviewing tests, youtube vids, dyno numbers etc. I would have loved to hit 470 on the dyno, but I knew statistically it would have been a rare expectation, however, 450-460 is far more common and sample sizes are much greater. I was aiming for 460rwhp and got what I was looking for.

If you replace the stock X-Pipe with the same X-Pipe of course you won't see gains, but dimensions do matter. That is in fact proven by basic physics and math, not ricer math.

So to properly answer the OP's question, Yes x-pipes are optional and yes they do provide gains within those conditions. Even CAI provide gains, under certain conditions which I stated multiple times and people refused to acknowledge those statements. I wasn't making blanket statements like upgrades don't do anything. And there are countless tests done proving my statements, but no one showed any evidence of X-Pipes not providing any gains at all. Just blanket statements without even the courtesy of ricer math to support it.

But honestly King, that's the thing about math, math can explain everything, and numbers don't lie unless the equation is wrong. Its easy to figure out my baseline without actually having one done. My car would have baselined between 395-400 based on what numbers I do have from the Dyno Tool, and testing done on the parts relative to other parts of the same type and same tests done. I took the law of large numbers, statistics and probability to guesstimate my baseline, and I think you would be surprised just how accurate that guess would be if I had a baseline done. I even proved there's no possible way I have a Unicorn that would have baselined for 420rwhp stock which also satisifed ALL of the conditions everyone stated to make it borderline impossible. And yet they still use that as the reason why the X-pipe doesn't do anything? The law of large numbers, Statistics and probability outweigh the butt dyno.

Ask yourself why I'm still using the stock axle-back exhaust on my car? For one reason, I am still researching axle-backs, and in that research everyone says axle-backs don't add power. Testing shows that to be true in MOST cases, but testing also shows it will likely improve fuel economy, but otherwise axle-backs are just for sound more than anything else. Well, sound is not what I'm chasing, and I'd rather be more icognito with the fuzz with the stock axle-back, but then again here's the double edged sword. I can drop probably 30-40 lbs off my ass end by switching to an aftermarket axle-back. But now I have to consider drone, which right now 3" MBRP with resonator is the highest potential pick for me. I cut weight, maybe improve fuel economy, and change the sound on the car to more of something I would like than the import tin can sound I get now. And now the kicker, I've been researching axle-backs since before last summer seen countless videos, sound clips, testing, and reviews regarding nothing but axle-backs. And I still have not decided yet. AWE, Borla, and Corsa, are far from the top of the list for me for many reasons, price not being one of the only reasons.

[David Gordon]

In the near future, I will put a mid length, rear catless X-pipe only, leaving stock catback alone. One of the cheaper models I saw for less than $300.

[ALMN]

Originally Posted by FlukeSS

Fair enough King, but you also confirmed what I said as well.

People should not be telling everyone an X-Pipe doesn't provide gains.

The fact is they do, under certain conditions, which my car meets some of those conditions because of the headers and cat delete. I didn't just randomly pick parts because I'm a cheap SOB. I chose the parts for a reason to build for longer term goals. As I stated before as well I did a ton of research on the parts I have before I commit to buying them. As much as months of research, reading, reviewing tests, youtube vids, dyno numbers etc. I would have loved to hit 470 on the dyno, but I knew statistically it would have been a rare expectation, however, 450-460 is far more common and sample sizes are much greater. I was aiming for 460rwhp and got what I was looking for.

If you replace the stock X-Pipe with the same X-Pipe of course you won't see gains, but dimensions do matter. That is in fact proven by basic physics and math, not ricer math.

So to properly answer the OP's question, Yes x-pipes are optional and yes they do provide gains within those conditions. Even CAI provide gains, under certain conditions which I stated multiple times and people refused to acknowledge those statements. I wasn't making blanket statements like upgrades don't do anything. And there are countless tests done proving my statements, but no one showed any evidence of X-Pipes not providing any gains at all. Just blanket statements without even the courtesy of ricer math to support it.

But honestly King, that's the thing about math, math can explain everything, and numbers don't lie unless the equation is wrong. Its easy to figure out my baseline without actually having one done. My car would have baselined between 395-400 based on what numbers I do have from the Dyno Tool, and testing done on the parts relative to other parts of the same type and same tests done. I took the law of large numbers, statistics and probability to guesstimate my baseline, and I think you would be surprised just how accurate that guess would be if I had a baseline done. I even proved there's no possible way I have a Unicorn that would have baselined for 420rwhp stock which also satisifed ALL of the conditions everyone stated to make it borderline impossible. And yet they still use that as the reason why the X-pipe doesn't do anything? The law of large numbers, Statistics and probability outweigh the butt dyno.

Ask yourself why I'm still using the stock axle-back exhaust on my car? For one reason, I am still researching axle-backs, and in that research everyone says axle-backs don't add power. Testing shows that to be true in MOST cases, but testing also shows it will likely improve fuel economy, but otherwise axle-backs are just for sound more than anything else. Well, sound is not what I'm chasing, and I'd rather be more icognito with the fuzz with the stock axle-back, but then again here's the double edged sword. I can drop probably 30-40 lbs off my ass end by switching to an aftermarket axle-back. But now I have to consider drone, which right now 3" MBRP with resonator is the highest potential pick for me. I cut weight, maybe improve fuel economy, and change the sound on the car to more of something I would like than the import tin can sound I get now. And now the kicker, I've been researching axle-backs since before last summer seen countless videos, sound clips, testing, and reviews regarding nothing but axle-backs. And I still have not decided yet. AWE, Borla, and Corsa, are far from the top of the list for me for many reasons, price not being one of the only reasons.

You are comparing stock X pipe to an aftermarket X pipe! I never said x pipe doesn’t do anything. Even going from 2.75” to 3”, you are not going to see anything. 7-10 hp is a magical number depending on a dyno, environmental conditions, fuel trim, so many variables. Even if that is you gained 7-10 hp from an x pipe, Corsa’s own website calls out for an increase of 6.5% of flow, which I would have a hard time believing, because I don’t know the condition of the stock exhaust that they tested against, does it have factory defects, dings, kinks. So many variables. If the 6.5% flow increase is giving you 7-10 hp to the wheels then the GM engineers should all quit their jobs and start working at Mc Donalds or something. Remember a dyno is only a tool but the real results are always shown at the track. If you want to get an accurate dyno reading, make sure the dyno is calibrated prior to the pulls and dynos are done before and after the mods same day with same entering air conditions. Even a heat soaked engine can show 10 to 20 whp difference on a dyno. That’s my last suggestion to anyone who loves dyno benchmarking to go test it out in the real world.

[FlukeSS]

Originally Posted by ALMN

You are comparing stock X pipe to an aftermarket X pipe! I never said x pipe doesn’t do anything. Even going from 2.75” to 3”, you are not going to see anything. 7-10 hp is a magical number depending on a dyno, environmental conditions, fuel trim, so many variables. Even if that is you gained 7-10 hp from an x pipe, Corsa’s own website calls out for an increase of 6.5% of flow, which I would have a hard time believing, because I don’t know the condition of the stock exhaust that they tested against, does it have factory defects, dings, kinks. So many variables. If the 6.5% flow increase is giving you 7-10 hp to the wheels then the GM engineers should all quit their jobs and start working at Mc Donalds or something. Remember a dyno is only a tool but the real results are always shown at the track. If you want to get an accurate dyno reading, make sure the dyno is calibrated prior to the pulls and dynos are done before and after the mods same day with same entering air conditions. Even a heat soaked engine can show 10 to 20 whp difference on a dyno. That’s my last suggestion to anyone who loves dyno benchmarking to go test it out in the real world.

I think that was my fault then, I misunderstood your statement clearly.

I quoted it here and re-read it.

Originally Posted by ALMN

Nope, not worth it unless you are going to switch to a full catback in the future. Stock exhaust also has an x pipe so just switching to another x pipe will have no effect on the noise or exhaust flow. That’s my opinion. Now if you do H pipe though, then your exhaust note would be more deeper but won’t flow freely as the X pipe.

But, everything I said was also true. I guess I was taking my car mods into account more than the OP.

If you switch the X-pipe to a larger diameter X-pipe than stock, it will show gains.

So your statement is not entirely true in that regard. Unless the "funnel" I think 6cycle was talking about later, remains the same on the 3" aftermarket X-pipe as it does the stock X-Pipe. In which case I see what you are saying.

But if it doesn't, then I am right, and you can't just arbitrarily say switching the x-pipe to an aftermarket doesn't do anything.

It does but it depends on what you get in that case.

And no, 7-12hp was not a magical number I made up, it was a test done relative to the same mods I have. Again, you are making blanket statements without considering the options. A 3" x-pipe will show a gain. Will it show a gain if none of your caveats are met? I never said it would, but based on physics, a larger diameter X-Pipe has more volumetric space for those exhaust gases being expelled by the stock headers would make that statement true, but by all means calculate the numbers yourself and factor in the delta of venturi effect as well.

That said, I assume if you did put an X-Pipe on in this situation you would cause an increase in back pressure would that not be true as well? That would be a bad thing in which case, I understand why you are saying not to do it if that was the case. But, that was a caveat I wasn't talking about. IF you are trying to suggest short term gains, then no an X-Pipe is not an option as you would be correct. But if you are building for a longer term goal like I am, then yes you would want one.

An X-Pipe will in fact show gains, and my mods fit nearly every single category you have stated to make that true, but yet you still insist it not being true, and when we use my car as an example you and others still deny the viability of the statement even when all of your caveats have been addressed.

You simply cannot explain away suggesting that my car is a unicorn with 420rwhp stock which is a huge statistical rarity.

Like I said, my statements are backed by math, statistics, probability, and actual testing not ricer math as King puts it.

[6spdhyperblue]

What would be the gains from a 4” xpipe?

Can you post the numbers with the Venturi effect? I’m actually decent at math

[FlukeSS]

Originally Posted by 6spdhyperblue

What would be the gains from a 4” xpipe?

Again backpressure is a concern, going too big will result in a lower power output.

There is a fine line of course.

I have 2" headers, 3" X-Pipe, no cats, and 2.75" stock axle back. (Again reason why I am considering 3" MBRP)

My full exhaust will be 3" with exception to the headers and the system itself should have an increase in venturi effect once I get rid of the suitcase.

My build intention is to remove as much of the restriction and bottlenecking as possible. And I'm building towards a longer term goal.

If the OP wants short term gains, then yes don't waste your money on an X-Pipe.

But also don't expect your dyno gains to be as high as other people as well. There are other factors as well, for example while I'm happy with my tuner, The next time I get my car tuned it will be by someone else. But I have 3 other big mods to get, before I get to that point, not including the Axle-back.

Like in my case I think that might explain why I wouldn't see a 470 on the dyno, I might have a backpressure issue because of my stock axle-back.