It's a very controversial topic in the Porsche community, but overall it seems like the people that really know what they are doing and build reliable good running engines avoid the iron sleeves (e.g. https://flat6innovations.com/cylinder-bore-scoring/). Like you said- it requires using loose clearances which makes for a noisy, oil burning, short lived, and low performance engine... not what you want in a Porsche.

The factory coatings do fail in some cases- usually in specific engine configurations with issues, but very often last 300k+ miles... on the smaller bore M96 engines cylinder/coating failures are almost unheard of, even with very high mileage and lots of hard track use. Personally, I'll just stick with the smaller bore engines, and in the unlikely event it fails get a good used block where the factory coating is still intact. There's tons of the 2.7 and 3.2 M96 Boxster engines out there still running great with 300k+ miles, and you can buy a good used one for a few grand.

>Like you said- it requires using loose clearances which makes for a noisy, oil burning, short lived, and low performance engine... not what you want in a Porsche.

Thats opposite of what I said :) Only the startup noise applies, but lets not pretend M96 sound great :)

When something becomes veblen good logic goes out the window. >$100K 30 year old car restorations arent meant to make them peak performers, it becomes matched numbers everything as factory wankfest for cars sitting in a collection or driven only occasionally on the weekends. There is very little incentive doing cheap repair when everyone believes in expensive ones.

>There's tons of the 2.7 and 3.2 M96 Boxster engines out there still running great with 300k+ miles, and you can buy a good used one for a few grand.

Wanna bet they all have scored cylinders? :) Same goes for BMW Nikasil, no such thing as cheap used block with intact coating.