My pic above was after 2600k. Then the misfires & cold start problems happened. Save my old AC delcos (ya ya) with 70k from before, put those back in and everything was as right as rain. As far as fuel economy, I didn't notice a difference because I was putting in the same amount every week with similar mileage (more or less). Horsepower/acceleration didn't notice a difference right up to that 2600k mark. The pic above explains the rest.