I've heard rumors the B20 sleeves are stronger, I've heard a lot more that is the exact oposite is true. I personally don't think Honda would put stronger sleeves in a motor they stick in a non-VTEC CRV than they do in their Type R cars but I believe they're physically different sleeves from the other standard B-series engines. I've talked to a few people online with B20's and turbo's who have had pretty sucessful experiences. Basically at low boost, I'd say less than 8psi, your basically more at the mercy of your tuning then you are at the engine physically being pushed beyond it's limits (although you are going to be pushing it beyond what it was orignally designed for). Even a sleeved engine with forged internals isn't going to survive a crappy tuning job that results in lots of detonation at 10 psi. It will last longer but it will still eventually fail.

Someone from before posted a good mantra for turbo Honda's. It's not a matter of if it's going to fail but when. Just something to keep in mind.