Saying hello

[GySgtFrank]

The side intake ports (on the irons) were placed there by Mazda for better low rpm drivability. The engines with the intake on the housings are known as a peripheral port engine. They produced lots of power, but didn't idle well enough for mass production. They are commonly used for racing though. The Renesis (RX-8) engine has also moved the exhaust ports to the irons for better efficiency. Again not as good for all out performance (turbos don't work well with them), but for what they're designed to do, they work very well.

Not quite sure what you mean by sleeve. If you're talking about the housings they are bolted together with long bolts through the irons and housings. The sleeve is commonly used to refer to the insert for the exhaust port in the housing.