yes i can not figure this one out .on e bay .125 over stock pass the big block selling for big money they are at the end of there life. and if you bore out to much you can hit water but if you do not the walls will move to thin and the rings will not seal . the wall help tie the top of the block the deck to the bottom of the crank case you are making it weaker i try to stop at 0.30 on small blocks and big block 396 at 0.40 big block 454 no more than 0.60 but this suff is getting hard to fined and good block are getting tuff to fine so look good be for you spend good money on junk. just be cause someome makes a pistons that size dose not mean you can bore it out that far 20 years a go i want the biggest big block in town so i sent out over 5 big blocks to get sonic check and one pass by the skin of it teeth that was when 4.250 cranks cost a lot of$$ so over bore was cheap way to get it up on CI