The main goal of the Redesigned Introductory Physics Lab (RIPL)project at Appalachian State is to improve student performance and attitudes in the algebra-based sequence. Modifications of the student lab experience were examined in terms of their impact on performance in the lecture portion, independent of the lecture instructor's pedagogical approach. Preliminary results for one lecture section, based on Modeling Instruction, indicate a large positive difference in all course measures for students in the redesigned lab compared to those in the more traditional lab offered by the department. On the other hand, FCI and other diagnostic scores show little difference between the two groups. While these measures indicate a discrepancy in the redesigned lab impact, an item-by-item analysis of the diagnostics reveals a rich story, one that can be used to improve both lecture and lab activities. In this paper, we examine some of the factors that strongly affect student performance, as well as the implications for the redesign process.