The Porsche(911) guys prefer Nicasil cylinders over the Alusil cylinders. One is a coating (Nicasil) and the Alusil is an Aluminum SIlicon matrix. The 944/928 blocks are Alusil without nicasil.
My Italian Husqvarna also has a Nicasil cylindercoating that is very hard, you replace rings not cylinders. Check out US chrome, there are other vendors that do it too.
Funny thing is BMW had a bigtime problem with their Nicasil blocks in the M60 V8 engines and had to recall most of them due to chipping, wear, oil usage and general durability problems. Go figure?