Union 76 station on Almaden Expressway at Foxworthy in San Jose
Union 76 station on 84 (Woodside Rd) west of El Camino sells 100 octane.

These are the only ones I know of, hope this helps.

 

I remember this link might change your idea on 100 octane.
http://theserviceadvisor.com/octane.htm#1

 

cls thanks for the help in reading your info they stated that we really didnot need high oct because the computers in our cars allow for lower oct. which is correct.. if memory serves me correctly this is done by mixture and retarding the timing which robs power...also 100 oct allows me to run my race program way faster thanks for the research rep for you......

 

so if I run 100 oct in the C4S(stock ecu), will I run into any problems???

 

can't see y your ecu should say woooozzzzzers good gas i'm gonna adv my timing and go really fast.imo

 

No problems but no real benifit. Blend in 100 oct to get 95 oct average.

This will give you the best performance for your stock ECU. Anymore will make it slower!!!

Disconnect the battery for 2 minutes after refuel. This will clear learned timing values on pump gas. If you don't do that it will take up to 100 miles for the ECU to reintroduce the timing. The ECU pulls timing real fast but is very slow to add it back in.

 

so blend 91oct with 100oct, will try it next time thanks...