i dont know how many of these guys have built / run b20 vtecs but ive owned one for 2 years . stock sleeves are not that week. poor/no tuning and high crankcase psi kill b20 blocks most of the time. if done right they can and will last . my block is even .5mm over bored so the sleeves are even thiner and she is still ticking . i rev my motor to 8500 and this is on 12.8 to 1 compression. im sure some will say im lucky but i know other wise.