Is it still Stage 1 with an intake? Where the line is on an EA888 Gen3

"Stock cars only" is the rule for this service, and the most common follow-up is "what about my intake?" The rule is not arbitrary, so the answer is not a flat no. It depends on whether the part changes what the calibration has to assume.

What Stage 1 assumes

A Stage 1 file assumes the factory turbo, the factory fuel system, the factory charge cooling and a factory-like exhaust restriction. Those four decide how much air the engine gets, how much fuel can be delivered to match, how hot the charge is, and how hard the turbo has to work to make a given boost. Change one and the file's targets are being met by different hardware; the boost control will chase the same number through a different path, and the safe margin the tuner left may be bigger or smaller than intended.

Parts that do not move the line

A drop-in panel filter. Same airbox, same sensor, same everything the ECU can see. Stage 1.

An aftermarket intake that keeps the factory sensor position. On the Gen3, the airflow is measured by a pressure sensor rather than a mass airflow meter, which makes the engine tolerant of intake changes that would upset an older car. A well-made intake is a small, real improvement in airflow and the file does not need to know. Stage 1, and say so on the form.

A cat-back exhaust. The part of the system behind the catalyst does not change what the turbo sees. Louder, not different. Stage 1.

Parts that move the line

A downpipe. The section between the turbo and the catalyst, especially one with a less restrictive catalyst or none, changes the turbine's back pressure. The turbo spools differently and the same wastegate position gives different boost. That is a different calibration, commonly sold as Stage 2, and a Stage 1 file on a downpipe car will behave unpredictably: sometimes over-boosting, sometimes throwing a fault for the catalyst monitor. Not Stage 1. It may also be illegal where you live for reasons unrelated to tuning.

A larger intercooler. Lower intake temperatures are good for the engine and a Stage 1 file benefits without knowing. This one sits on the line: it does not require a different file, but the tuner wants to know, because a cool log from an upgraded intercooler tells a different story from a cool log on a stock one.

A turbo, an injector, a fuel pump. Not Stage 1 by any definition. The file's whole basis changes.

Why the form asks in detail

The booking form has a modifications section for exactly this. It is not a trap; a car with a panel filter and a cat-back is still a Stage 1 car and will be booked as one. A car with a downpipe is a conversation before any money moves, because the honest answer might be "not yet, not from this service". The worst outcome is a Stage 1 file on a Stage 2 car that nobody mentioned, and the form is how that outcome is avoided.

The simulator below has no modification sliders, only the calibration ones, which is a fair picture of what Stage 1 is: the file, on the hardware the factory fitted.