Which exhaust system would be considered correct for a November 64 San Jose A code? My car has a single exhaust on it but I am not sure if it is factory correct. I was wondering if there was a factory dual exhaust available for this car or if it was only available on K code cars? The NPD catalog appears to only specify a dual exhaust system for a HIPO car. One application specifies 289 HIPO before 10/64 (12/64 on San Jose cars), and the other specifies 289 HIPO after 10/64 (arvinode). It is kind of confusing. I really would like to put dual exhausts on this car, but if it was not offered as an option, I'll leave the single exhaust on it.