I had an LSVTEC for 3 years on a stock bottomend it never blew I just rebuilt it. I never went above 8grand either.

 

The b20 sleeves are definately weaker than the ls sleeves, but if you are gonna sleeve a block, just get a b18 and sleeve it to 84mm, and then you have a 2.0 liter b18. That way will save you money in the long run. If you are boosting a b20 block, I have seen pics of a cracked sleeve at 8psi after only 2 weeks, just a warning