Bottom line on our GB's, the volume for higher ticket items drops off quickly and the pattern is a buy and hold if the distributor can manage that. Finding crossover sales to support development is the best path whether through like platform models" eg. the FX/350 Z chassis and GT Spec, other forums eg. the org, or finding products that cross over that can be cross sold that have not yet been exploited like the INJEN CAI on my VK that will fit 06+VK's that INJEN won't jump on (that really just needs a minor bracket tweak and is a very slick CAI). Chassis mods apply to both 1st gens, performance mods have a much bigger pool with the VQ (VK is obviously growing) 2nd gens are wanting everything......
Appreciate your help in looking into GB's and possibly doing some DEV work. In a lot of ways it's a labor of love for the FX and the return would be long term. You do however have a receptive audience and the audience is growing as FX prices drop over time.