A stiffener assembly for use with testing devices is provided herein. The second path is substantially parallel to the first path. The outer shell consists of two half shells, each having a reinforcing segment. When the internal pressure detected by the pressure detector reaches its peak after the combustion starting time has been detected, the crank angle at this time point is determined to correspond to the maximum internal cylinder pressure that is generated by combustion. The display system may implement a spatial and temporal image processing, digital shutter controls, rolling shutter controls, sequential color output, adaptive dynamic sensor feedback, frame rate matching, motion compensated field sequencing and a variety of other techniques to produce a high quality display output. If any transaction has not committed, the second server enforces uncommitted state of the identified set by blocking completion of the identified set issued in the first session.