Except if intended for a really very low funds race only car or truck the firewall need to by no means be modified to accommodate the cooling program or even the ignition process with a 20v conversion, there isn't any will need with the right parts. The original 20V distributor https://toyota-4age-blacktop-engi04703.shotblogs.com/the-ultimate-guide-to-toyota-4a-ge-45388827