[Kponti]

Its Another One (DeeJaaay Kalid voice)

All the below is with ER catless secondaries.

SO I did a H-pipe resonator delete. Car sounded great, perfect tone, zero drone. But I kept getting this weird sound above 6000rpm like blowing through a straw.
After a couple of months, drove me crazy so I had the H connector removed. The whistling sound was a lot less but still present. However, the tone changed a little at part-throttle driving. Sounded like more drone with the volume a little louder than I wanted.

Switched it out for an Xpipe just on Monday. Zero drone (albeit was not much at all, to begin with), the car is less loud compared to the H or straight pipes, but louder than with stock resonator. It definitely seems louder outside the car than when I had the H pipe.

All the above are just sound observations, however, I have some surprising dragy results to share later today.

[Kponti]

So for the 0-60mph. This is with the H-pipe on both sets. I did a lot more runs but used the lowest and highest runs that weren't blown with too much wheelspin or a bog.

This is with launch control

[Kponti]

Same H pipe brake boosting

[Kponti]

Then I had the X pipe installed and this was my first run Brake boosting alone

[Kponti]

After a few days I got this

[Kponti]

So the result is the car lost some low end when launching and needed to be brake boosted a bit more to get better 0-60mph times.

It feels a lot punchier at part throttle after a few days with the X-pipe. Yet it seems to build boost slower off the line.
Since it made that much of a difference, I am going to test more on what else changed.

[Kponti]

Unfortunately, my impatience got the better of me so I did not get any LC runs with the X-pipe to compare.

I flashed the xHP stage 3 on the car this morning while waiting to see if the weather would improve for some LC runs (rained crappy weather the past few days). So all times posted after this will be with the trans tune applied which will obviously skew the results.

[Tenac]

Your timing on the runs on seconds away from each other? Like the actual time 5am or pm??

[Kponti]

Originally Posted by Tenac

Your timing on the runs on seconds away from each other? Like the actual time 5am or pm??

Screenshots of my dragy history. Pm not am

[mpop302]

what mods do you have to hit 2.6? I assume coupe

My resonator hx is interested
I had an X pipe on the coupe and absolutely loved it. Perfect growl, no drone

Then I moved on to a gran coupe, and decided to do straight pipe instead to compensate for longer exhaust. It was too loud and had too much drone.

I then created an H pipe from straight on the GC, and the sound became better but still i hear a slight bit of drone.

Contemplating going X pipe on the GC, but worried I may never achieve the sound i had with the coupe

Performance wise, butt dyno didnt notice any difference

[Kponti]

Originally Posted by mpop302

what mods do you have to hit 2.6? I assume coupe

My resonator hx is interested
I had an X pipe on the coupe and absolutely loved it. Perfect growl, no drone

Then I moved on to a gran coupe, and decided to do straight pipe instead to compensate for longer exhaust. It was too loud and had too much drone.

I then created an H pipe from straight on the GC, and the sound became better but still i hear a slight bit of drone.

Contemplating going X pipe on the GC, but worried I may never achieve the sound i had with the coupe

Performance wise, butt dyno didnt notice any difference

Racechip, secondary catless DP, Dinan inlet

Butt dyno felt a change (not in a good way) hence the draggy testing

[rdown1976]

So do you recommend the h pipe or x pipe?

[pbonsalb]

Does Kponti have an M850i or an M8? If M850i, I can see the X or H having a bigger effect than on an M8 since the M850i does not have a crossover manifold and the M8 does. If he does have an M8, then the results are more interesting. I had not seen draggy results of X versus H before and figured the difference was mostly sound. There is some testing on late model Mustangs and the results were not conclusive.

On a naturally aspirated car, it can also matter where the X or H is located in the exhaust. I am not sure it matters as much on a turbo car and particularly an M5/8 with the crossover manifold.

[Kponti]

Originally Posted by rdown1976

So do you recommend the h pipe or x pipe?

H pipe for more sound and better low end (slight and I mean slight increase in drone that is not intrusive)

[Kponti]

Originally Posted by pbonsalb

Does Kponti have an M850i or an M8? If M850i, I can see the X or H having a bigger effect than on an M8 since the M850i does not have a crossover manifold and the M8 does. If he does have an M8, then the results are more interesting. I had not seen draggy results of X versus H before and figured the difference was mostly sound. There is some testing on late model Mustangs and the results were not conclusive.

On a naturally aspirated car, it can also matter where the X or H is located in the exhaust. I am not sure it matters as much on a turbo car and particularly an M5/8 with the crossover manifold.

M8 coupe (competition)

I kept the X pipe because in the end it did not affect my trap speeds and the trans tuning made up for the loss of low end
Ran a best of 10.3@133mph with the same mods

[rdown1976]

Why is the X hurting low end?

[rdown1976]

Also, do you just walk in to an exhaust shop and say you want an x or h pipe and they can make you one and install?

[Kponti]

Originally Posted by rdown1976

Why is the X hurting low end?

I am actually not sure, but I think the torque comes back up and more than makes up for it in just a few hundred rpm.
In the end, it did not matter much when launch control was added to the mix. Brake boosting was the only time I saw a difference (when xHP is disabled)

[Kponti]

Originally Posted by rdown1976

Also, do you just walk in to an exhaust shop and say you want an x or h pipe and they can make you one and install?

Yes probably around $200

[pbonsalb]

Originally Posted by rdown1976

Also, do you just walk in to an exhaust shop and say you want an x or h pipe and they can make you one and install?

Some say the H does not reduce backpressure as much as the X. Backpressure helps low end torque but costs power on the top end. If you do some research on the internet, you will see that the consensus is that neither H nor X have a significant advantage over the other in terms of performance. This is even more true on a turbo car and particularly on a turbo car with crossover manifold. Kponti has tried both, though the H pipe draggy benefitted from better DA. He also has butt dyno observations, but I do not believe the torque and power differences are enough for a butt to register. Maybe at 1000 - 2000 rpm trundling around town at part throttle where the engine is making only 100 hp you could feel 5 lbs more or less torque but I would want to see dynos.