Compression issues more likely to be caused by irons or housings?
 

Assuming normal wear and tear(no shattered apex seals), are low compression issues more likely to be caused by the irons or the aluminum housings?

both really, your side seals, apex seals, corner seals, irons and housings ALL contribute to sealing/compression. There really isn't a "more likely" scenario because EVERY engine wears differently

So, the fact that the housings are made of a softer metal than the irons doesn't make a difference in normal wear?

The aluminum housings are steel lined and coated in chrome. They're just as hard as the irons.

The rotor housings usually show more wear than the irons during tear down.

Side and corner seals really don't wear that much.

Primary wear surfaces are the housings and apex seals.

If you have the stupid OEM 3 piece seals, your apex seal wear limits are cut in half from the 2 piece seal.

Usually the housing wears most where the corner piece of the apex seal rides.

High mile irons will show a football shaped wear pattern from the side/corner seals. There can be a LOT of wear on these and still be very usable.

Good stuff, thanks for the info.