Rasputin.

Ah, you installed a new system. That would certainly provide some torque gains.

lovetoturn

Another viewpoint on this topic.

Porsche is very proud of the sounds their cars make, and they have a special room just to test and adjust the tone of their exhausts. They have tuned the GT4 to sound a certain way and want that to be uniform throughout the world. When you remove the GPF, as we all know, more low rpm drone is introduced into the sound signature. Of course, no one likes that, and it not tolerable for the manufacturer. Porsche would have to modify the exhaust in other ways to cure that problem for just a few markets. Bean counters are not going for that at all.

James88

Does the ecu require to be flash tuned if you remove these filters, would there be a cell error ?

TXshaggy

Don’t know why you wouldn’t have gains. It’s the equivalent of a cat, everyone agrees removing/hiflow cats produces power.

CaptainSlowly

I think I saw a video where AP said it was so that GT4’s sound the same regardless of country

Bill Mitchell

I knocked the matrix out of a set of OEM GPF'S that I bought from another RL member and swapped them onto my GTS 4.0. The sound is slightly louder and maybe a bit more performance. There's a whole thread titled "Big genitalia mod" discussing it, there are no monitors in the US, some claim the matrix is inert. Mine was grey in color and they were used. Several aftermarket companies offer replacement pipes , Soul, Akrapovic, etc.

phefner

Not for US cars. Replaced mine with OAPs from Akrapovic after the break-in.

Bob Z.

Forgot whatever the purpose is supposed to be and get rid of them. They weigh a lot, do not improve the sound and the cost to replace them is not a lot so just do it!

Bill_76

I got delivery with the valves locked fully open, sounds louder at low rpms but it sounds fake, sinthetic, I hate it from the first mile after delivery.
First I swap the rear muffler for a Soul
valved, so much better sound than stock, but little bit louder than Oem mainly below 5k rpm (always with valves fully open), so I decided to take out the OPFs but wanted an OAP with muffler, so I sold the Soul and bought the Kline, and the torque/power difference only happened when the OAP was deleted. My friend bought my soul rear muffler and added akra oap and same opinion so much alive at low/mid rpms.

Here the guy in question

James88

Thanks, OAPs is over axle pipes? Just replaced with pipes?

Tief Lernen

No one has ever posted a dyno running showing a gain in HP/torque from removing the OAPs. The only one I've seen actually showed a slight drop in the middle of the RPM range (probably just normal variation between runs).

Westcoast

I have never seen published information to support this idea, can you share the source? I have read that the GPF on NA cars is inert.

JCviggen

The US cars do have an inert matrix, and the difference between functional and non-functional ones is very clear even visually. I believe it was JCR who posted pictures of the difference.

AdamIsAdam

I had the dealer install my Flat-6 OAP pipes prior to delivery. I didn't want to drive it even one mile stock. I drove friends' cars, some stock, some with OAP pipes. For me, there was no other choice.

Oh, and with Cartronics EV controller installed I can easily switch off the drone when quiet driving is desired.

Love it.

Larry Cable

NO