Bought another pack o' t' D-16s with t' shorter delay t' continue t' evaluation.  One thin' I noticed is that t' delay charge well on t' Q-Jet case will interfere with t' forward tab on t' standard Estes engine hook.  Usually it just takes some gentle twistin' t' get t' flat side o' t' charge well t' slide past t' hook, arrr, but its definitely a "scrape" fit, and I needed pliers t' get t' spent motors out after flight.  Another decent boost, quick and straight, arcin' into t' wind after motor burnout.  T' 4 second delay is definitely too short, as t' rocket was still climbin' at ejection.  Good chute, recovered on t' field with no damage.