Fitting new s/s manifold exhaust and sports cat

  1. My model of MX-5 is: MK2.5
  2. I’m based near: _Cambridgeshire _
  3. I’m looking for technical help or recommendations on: __fitting new exhaust manifold and sports cat.
    Need bit of advice please if this would need any extra technical parts adding regards sensors etc it’s all stainless steel. Can I just swap over.
    I am total novice
    Any advice greatly appreciated

O2 wiring might need extending. Reuse the metal manifold-head gasket, not the (usually) cheap effort supplied with a manifold.

Manifolds often need a bit of wiggling to get in place. Once you have fitted it, before you start up, give the manifold a good wipe over with white spirit, to removed any greast. When the manifold warm, it passivates. There is an oxidation process. A nice clean surface will passivate to a golden colour. Old engine oil gives a more purple colour. If you leave fingerprints on it, these become visible forever.

A 1.8 manifold, when new, that I didn’t do this for:


After a few years


Another one that I did clean

After passivation


HI saz9961
That’s great thank you very much for the advice

Neat info Saz, wish I’d known this a couple of weeks ago when I fitted mine.
Nigel, the manifold for my mkII 1.8 was bought from MX5PARTS.
The O2 sensor wiring needed extending by 0.5m+.
Also, check for clearance against the floorpan/passenger footwell. Mine touches and is noisy as anything. I am going to have to take it all off again and do some modifications.
One last thing, if your MK2.5 is similar to my mkII you may have a challenge connecting the EGR pipe but others may be able to shed more light on that. I’m not sure whether the pipes run the same way on each model.
Good luck with your project :+1:

Thanks very much, much appreciated

1 Like

I also tried a MX5parts 1.8 stainless steel manifold that knocked against the bulkhead, they sent me a replacement that did exactly the same so I bit the bullet and bought a RacingBeat one. Nice quality & fitted like a glove

1 Like