the squish discussion is fairly irrelevant to rallycar's turbo engine. much more important to get the CR right than to worry too much about squish.

besides, with EFI the mixtures are (well, should be!) alot better and more consistent than old carby engines anyway and squish is not as important.

squish was a technique used to help control detonation in high CR engines in the olden days :P Well, high CR for the fuel used and combustion chamber design and material used. It is of less importance in lower CR engines.

modern engine designes with do not use squish to any real degree with their pent-roof chambers. The fuel injected in such a fine mist under high pressure provides a very good even combustible mix, so squich is of little advantage.