scoobyboy34

I was planning on fitting a set of stainless steel performance headers made by Megan on a MY94 STi. The question on my mind is if I fit these headers and replace just the downpipe cat for the next MOT, would it pass? There is a sensor in the standard manifold, but not one in the Megan set. Has anyone here had any issues with this, or have recently had their car tested with a performance set of headers? Cheers, Steve.

Normski

The sensor in your standard headers is the lambda sensor. This is a critical sensor for the operation of the engine management come MOT time.

Early cars have them in the headers and later ones have it at the top of the downpipe. So you have some options.

1. Use the Megan headers with a standard cat downpipe from a later car, moving the lambda.
2. Use the Megan headers and get your downpipe drilled and tapped, moving the lambda.
3. (i'm not sure if any do but) Use a different set of headers that have a lambda boss in the same position as standard.

scoobyboy34

The original cat downpipe also has a sensor in it, so would I need both (headers and downpipe) for the MOT??

BUDWRX

so u can just move the sensor to after the turbo then? as i have the same prob

Cornelius

iTrader: (2)

I've got the HKS headers on my classic (JDM MY'96), I just put the catted centre on the car for MOT's as it's easier and quicker to replace than the downpipe, and it passes the emissions ok

harvey

iTrader: (48)

Numerous people on here have had problems with Megan headers splitting.
Tubular headers are likely to slug your spool unless the primaries and collector are specifically designed for your turbo air flow.