Hi again Spook,

As you note, few people (Volvo engineers and others wanting to get some of the aftermarket business) would know what would happen when you use a non EGR CAT on an EGR engine exhaust.

On using a turbo CAT, thanks for the suggestion. I will check diameter and OAL size differences. I suspect 1/8" to 1/4" diameter difference which would not be too much to make up at the back end. However the front-end flares and cupped cast iron gasket is yet another challenge to get then air tight ...all assuming flow rate is the limiting factor. I suspect the difference is with the core of the CAT element size itself and/or precious metal contents.

The Rod added a post to your first reply that he has used a '94 940 w/EGR CAT on a '95 940 w/EGR and PULSAIR (*) with no fit problems. This adds that '95 is not a special year with PULSAIR added, but leaves the EGR exhaust 'engineering' question up for discussion.

* In '95, Volvo added PULSAIR ...which goes one better than EGR. PULSAIR adds air at a critical point when the exhaust valve opens to lower exhaust gas temperature and create more combustion later on in the exhaust system.

...still have a few other exhaust experts to check out.

Will let you know what I turn up.

AndréD