REGULAR =87 OCT..
I agree about the Stage1 deal. IF your fuel/boost is modified in any way to give you more power. You SHOULD by all means use anything BUT regular.
Unless you can physically turn down the boost & adjust the fuel yourself, then do not use regular. Remember more boost is an artifical compression increaser. As we all know higher compression, requires better grade( higher octane) fuel. Start with hi test, then slowly add mid grade, if you like, but if you notice ANY detonation, STOP USING IT!!! You can very well melt pistions this way.
I'm not used to PT cruiser Stages. With DSM's( just abotu any other turbo car i've worked on) we use dataloggers, A/F gauges, EGT gauges, laptops, ect..
We dont rely on factory stages of modification..we WANT to know what is going on. Not hope the factory has it right.
Hence a 4g63 just went 8.13 @ 177mph in the 1/4 mile. YES a 4 cylinder
