Just very general question about equal length headers.
If on a classic shape Impreza you swapped say from the standard cast manifold to Equal length stainless headers. How well does the Lambda and ecu cope with the change, does it throw any fault codes

 

have a word with Harvey mate, I've heard his headers are the best and he'll be able to tell you about ecu etc

 

+1 to above,Harvey really is one of the best to sort you out with headers and uppipe's,in fact he can sort you out with pretty much anything subaru[Oh yes and FMIC are a speciality]

 

Thanks for the replies guys, have heard Harveys ported headers are good. Was asking the question more regards equal length headers and how the ECU responds to the lambda signal generated from using equal length rather than the standard unequal length. More out of interest I guess

 

Can of worms...

Do you mean actual equal length ? Or just less un-equal length ?

Mine are clearly more equal then OEM, but not anywhere near equal as used on a twin scroll set-up.

You gain mid-range torque and upper rpm power, but lose some of the burble at idle.
You need to map the car for the maximum benefit, like most people mine were fitted with a larger turbo and a larger exhaust all at once, so a re-re-map was needed.

Well mine did !

dunx

 

The lambda is only used for off-boost driving, so I imagine it will cope just fine with the header change.

But on-boost will be a different story as the exhaust flow will be different, affecting turbo spool with the potential for boost spikes. You may be OK, but I wouldn't risk driving it on boost without checking fuelling using a wideband, probably on a rolling road, and I would prepare myself for the likelihood of needing a remap.

Also, any benefit to be had is unlikely to be realised without a remap anyway.