[AMG KLR]

Hi all, as title suggests, does adding a downpipe to MPPK give an increase in horsepower (IE: can it take advantage of the MPPK tuning) or to the car, is it simply just more breathable and louder with minimal HP gains. Of course I know the CEL would need to be handled. Thanks

[weehe126]

The tune is meant for a stock cat, so it won't be optimized for catless. You will only get a few hp at best.

[Skyhigh]

"Downpipe" does not necessarily mean catless. There are downpipes with sport cat converters which in my opinion are the better choice for a number of reasons, although clearly more expensive.

A downpipe will give you power and torque gains (somewhere in the range of 10-20 PS) with or without MPPK.

[mike@x-ph.com]

it'll give you more sound and power. Of course, you'll make a lot more power if you change your tune

[kern417]

negligible gains if any

[Skyhigh]

Depends on the definition of "negligible". If 15-20PS are negligible, then yes.

[weehe126]

People claiming hp gains with no tuning changes need to post some proof.

[Skyhigh]

Originally Posted by weehe126

People claiming hp gains with no tuning changes need to post some proof.

I have. You can find my review in another thread.
In my case - roughly quarter of a second improvement 0-100 with a catted DP, no other hardware or software changes.
It exceeded my expectations as well.

[johnung]

Originally Posted by weehe126

People claiming hp gains with no tuning changes need to post some proof.

No one has to post proof. It's common knowledge that a freer flowing catted or catless downpipe will provide a small performance bump by reducing backpressure against the turbo. No one is claiming that it's even a 10% increase. It's a small bump at best. No reason to ask anyone for factual data unless someone makes an outrageous claim.

[yokata]

Originally Posted by weehe126

People claiming hp gains with no tuning changes need to post some proof.

Thats mppsk with dp with no tune vs bm3 st2 ots 100ron

[Skyhigh]

You are saying +50PS and +110NM from just a DP!??
That dyno needs some serious recalibration..... 😄

On B58 a (catted) DP brings 15-25 PS and ~20NM. Catless gains would be slightly higher, but not dramatically.
To me that's still appreciable from just a DP, but nowhere near 50PS and over 100NM.

[yokata]

Originally Posted by Skyhigh

You are saying +50PS and +110NM from just a DP!??
That dyno needs some serious recalibration..... 😄

On B58 a (catted) DP brings 15-25 PS and ~20NM. Catless gains would be slightly higher, but not dramatically.
To me that's still appreciable from just a DP, but nowhere near 50PS and over 100NM.

My old n55 made 403hp bm3 st2 and on a mustang dyno 335whp (dynojet should be 350-60) so i think its accurate

[Skyhigh]

The numbers on your diagram for MPPSK and DP only are simply (very) far from realistic. That's all I know. And I did a lot of research before buying my DP, saw a lot of videos and dyno runs.

Here a good summary for B58:

https://bmwtuning.co/bmw-b58-upgraded-downpipe-guide/

[weehe126]

No one is questioning if you change the tune you will get more power with a dp.

[kern417]

Originally Posted by yokata

My old n55 made 403hp bm3 st2 and on a mustang dyno 335whp (dynojet should be 350-60) so i think its accurate

Originally Posted by Skyhigh

The numbers on your diagram for MPPSK and DP only are simply (very) far from realistic. That's all I know. And I did a lot of research before buying my DP, saw a lot of videos and dyno runs.

Here a good summary for B58:

https://bmwtuning.co/bmw-b58-upgraded-downpipe-guide/

you too are speaking to 2 different topics. yokata is showing gains with a tune while Skyhigh is saying just a downpipe without a flash.

Originally Posted by pwaf13

For what it's worth (and I'm starting to think Dyno operators may have borked my first run when looking at speeds etc suggests diff gears ) but this is my 340i MPPSK and BM3 Stage 1 93 vs MPPSK, VRSF catted downpipe, MST intake BM3 Stage 2 93

Gained next to no HP peak with c20hp mid range gains, and a very decent and noticeable slug of torque c35 lbft

Skyhigh although he thinks the dyno isn't accurate, this is how you can make a car faster without increasing hp. Just a downpipe alone will improve flow and spool which makes a wider power band but it does not increase hp alone. You're also relying on the car to compensate in the DME for the new characteristics which isn't ideal but again manageable/negligible.

[Stampe]

25 hp more with only hjs 300 cel cat, no software .
look at 15:30

[Skyhigh]

I've watched the above video many times, as I was contemplating getting the same DP. I do not fully trust the results (they admit the temperature was also lower the second time).

+25 PS and +37 NM sounds a bit too much from a 300 cell DP, considering Akrapovic, who, with a more optimised DP design and precisely the same HJS cat. conv. claim +17PS and +18NM. So the truth for me is that for B58, a catted DP brings a gain of 15-20 PS and about 20-25 NM. More importantly, as already mentioned - a wider power-band all the way to the top.

In my case that is definitely the case, as my 0-100 time dropped with 0,2-0,25 sec instantly.