GR86 GT86 vs GR86 Exhaust fitments

[SJR202]

Hi
I know there is an exhaust thread but thought this might be specific enough to have its own, Im considering an experiment with a 2nd cat delete and on the GT86 there is a relatively cheap straight pipe option - e.g. Berk Technology Test Pipe (BT8603) which is OEM fitment for the GT which is what Im looking to try.

Does this pipe section replicate a GR85 section for a like for like swap out? Im assuming unlikely but wondered if anyone who has played with GT and GR exhausts could confirm how similar they are?

Thanks

 

[ZN8]

On the cat equipped US cars it's the same don't know about the GPF equipped cars over here in Europe.

 

[GRistopher]

I can confirm that US spec centre pipe-back exhausts fit (I'm running one) so I'd assume the centre pipe is a very similar size /shape.

As ZN8 said, it's not a second cat on eu/uk cars, but a GPF. I'm not sure what they have in the way of sensors and if so what you would have to do if you put a straight pipe in its place. I'd be very intrigued to find out though.

 

[ZN8]

Ah yeah good point on the sensors. There are pressure sensors in the front pipe. So it's not going to work, even if you had bungs installed on the front pipe you will trigger the EML.

 

[SJR202]

Ah yeah good point on the sensors. There are pressure sensors in the front pipe. So it's not going to work, even if you had bungs installed on the front pipe you will trigger the EML.

Not sure I follow sorry. Do you mean by removing the 2nd Cat the lack of back pressure to the 1st Cat would trigger an EML?
Is it the GPF thats the next box down from the 2nd Cat? What if that went straight through?

 

[ZN8]

There is no second cat it is a GPF. The small box at the rear of the front pipe is a Helmholtz resonator.

The ECU will measure the differential pressure between the entry and exit of the GPF to identify if it gets fouled up. If you remove the GPF it will flag the EML as the pressure measurement will go out of its expected operating range.

 

[Conscript]

There is no second cat it is a GPF. The small box at the rear of the front pipe is a Helmholtz resonator.

The ECU will measure the differential pressure between the entry and exit of the GPF to identify if it gets fouled up. If you remove the GPF it will flag the EML as the pressure measurement will go out of its expected operating range.

I guess that knocks all catless manifold options into a cocked hat then? Used to be able to get away with them and hot second cat to pass emissions.
Unless the GPF does a similar job.

 

[ZN8]

Yeap. Kinda why I never got too excited about exhaust manifolds and went for a non resonated cat back as I knew I couldn't replace any other part. 1 GPF and 1 Cat you can't be without either to pass an MOT. GPF internals are ceramic I think, so don't have any catalytic properties.