In Case You Missed It
Mind the Gap
An ill-fitting joint where the wing joins the fuselage doesn't leap to mind as a foremost source of induced drag, but the effects can be significant.
Wind Tunnel
When unexpected drag is an issue, the cause could be gaps in the skin of your airplane. A simple seal might solve the problem.
All About Avionics, Part 7
If you intend to fly non-precision or precision GPS approaches, you really do need an IFR GPS. This article explains the options available and the legal issues associated with using the latest in-cockpit GPS technology for IFR navigation; by Stein Bruch.