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      11-05-2021, 03:17 AM   #1
2978386166
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cat less downpipe decrease acceleration

Hi bimmers, I am wondering if anyone had experience on bmw x5/x6 m50i models specifically on modified downpipe.

I heard that a cattless downpipe decreases torque at lower rpms, would it be very significant? How worth it was the extra sound compared to the decrease in torque?

thank you!
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      11-05-2021, 06:48 AM   #2
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Ive not heard of any decrease but if so it will not really be noticeable.
On the other hand, the sound difference will certainly be noticeable.
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      11-15-2021, 07:35 AM   #3
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Quote:
Originally Posted by 2978386166 View Post
Hi bimmers, I am wondering if anyone had experience on bmw x5/x6 m50i models specifically on modified downpipe.

I heard that a cattless downpipe decreases torque at lower rpms, would it be very significant? How worth it was the extra sound compared to the decrease in torque?

thank you!
i have tune and vrsf catless downpipe and haven't experienced any loss of torque it helps my turbo spool and only made my car faster
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      11-16-2021, 12:25 PM   #4
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Can't speak for the 50i, but my 40i spools faster/louder and pulls hard. Although, I also have a tune and the M performance exhaust.

I had catless dps on my N54 335i and it was day and night.
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      11-16-2021, 01:16 PM   #5
simrag
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Quote:
Originally Posted by 2978386166 View Post
Hi bimmers, I am wondering if anyone had experience on bmw x5/x6 m50i models specifically on modified downpipe.

I heard that a cattless downpipe decreases torque at lower rpms, would it be very significant? How worth it was the extra sound compared to the decrease in torque?

thank you!
No first hand experience with a M50i, but you never lose reducing backpressure in the downpipe with a turbocharged engine. Less backpressure = better spool = more low end power.
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      11-19-2021, 12:59 PM   #6
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Quote:
Originally Posted by simrag View Post
No first hand experience with a M50i, but you never lose reducing backpressure in the downpipe with a turbocharged engine. Less backpressure = better spool = more low end power.
This is correct...

Even without turbo's the old theory of backpressure equaling low end power is at best situational, at worst an old wives tail. I can't count the number of non turbo cars I saw removing cats and opening up exhausts when I was in the tuner world and I never once saw a dyno drop power because of it.
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