http://www.scoob.co.uk/typer/ej257build/block.jpg
That is the inserts i mentioned, interference fit.
I thought that the 22B was a semi closed deck block.
2.5 standard block is an ideal fast road car, and imo with rods and pistons and bearings should be fairly safe for 450bhp, after that i am not sure, there are lots of guys that vouch for them for over 500, but there has been a good few failures, the top of the bores are very badly supported where it needs to be, that with inconsistant block cases from Subaru, reports of new engines being oil guzzlers, or having piston slap due to not been honed or torqued correct, bores being oval etc etc
More and more are now adding support, this has been done for a good while by the yanks and Aussies, seems to be getting more popular in UK now,
Liners are extremely strong, but they have to be flawlessly machined and installed, liners dropping and causing headgasket failure is probably most common sympton, heard of liners spinning aswell.
Seen as do the power you have been at already Al, i presume your going for 500 or 550
With a great selection of direct fit 500+ turbos now available i was thinking the same, and guess what???
I purchased myself a newly BUILT 2.35 BASED ON EJ22T CLOSED DECK