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BMW M8 Forum and 8 Series Forum BMW M8 and 8-Series General Discussion Xpipe vs Hpipe/Straight pipe (Resonator delete)

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      12-22-2023, 11:22 AM   #1
Kponti
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Xpipe vs Hpipe/Straight pipe (Resonator delete)

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.
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      12-22-2023, 11:23 AM   #2
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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
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      12-22-2023, 04:57 PM   #3
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Same H pipe brake boosting
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      12-22-2023, 05:03 PM   #4
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Then I had the X pipe installed and this was my first run Brake boosting alone
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      12-22-2023, 05:06 PM   #5
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After a few days I got this
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      12-22-2023, 05:56 PM   #6
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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.
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      12-24-2023, 01:07 PM   #7
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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.
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      12-24-2023, 01:38 PM   #8
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Your timing on the runs on seconds away from each other? Like the actual time 5am or pm??
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      12-24-2023, 08:31 PM   #9
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Quote:
Originally Posted by Tenac View Post
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
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      12-28-2023, 03:32 PM   #10
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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
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      12-28-2023, 06:22 PM   #11
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Quote:
Originally Posted by mpop302 View Post
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
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