Mine is 1) The 2 capacitor, 2 diode signal strength meter mod. This $2.00 mod is great for a scanner without a signal strength indicator. Will drive any meter and is great for antenna comparisons. 2) The 6400 channel memory add-on. cheap parts average install time. Proof that "I've got more memory than you" was around long before DMA and OOMM. I wonder if the Guinness Book of World Records has a record for "The fastest time to program a PRO 2006 with 6400 channels By Hand" ?