tense

Which sentence has the correct tense:
a. Yesterday, I was driving to John's place thinking about what he said to me two days before.
b. Yesterday, I was driving to John's place thinking about what he had said to me two days before.

[Mister Micawber]

Both are OK, but the past perfect is redundant, as you have clearly identified the precedence of the actions by expliciting stating 'two days before'. The past perfect should be reserved for cases where it is required in order to define this precedence or isolate the earlier from the later action.