Why go 2.1 and not say at 2.0 is it just the fact that you can use calibre pistons? what power gain would you get say over a 2.1 instead of 1.8 (i have 1.8 btw) but never bother thinking about 2.1 how much could you do a 2.1 with calibra pistons and modded rods?

Also any one know all the bits you have to do and need to do a 2.1 and rough cost (parts only no labour)