first of all before someone start saying stupid reply. i'm not new here on this forum but i'm new to the force induction scene with dropping out of NA motors lately. i'm having a debate wheter them darton mid-sleeves for B18C can be safe bore out to 86mm with going to a max boost of 30psi? i have pactically every other componet for this setup already just not the turbo and the sleeves boring...or which size do some of you guys perfer?

 

86mm is too large for boost, any small gains you might see aren't worth the tradeoff of potential headgasket sealing problems. Run no larger than an 83-84mm bore to start with and you'll be fine, 86mm isn't worth it boosted.

 

well in that case then...84 should be fine since they can come in those bore already