My series 6 didn't have a razorback tube installed and I added one about 3 inches high at the forward edge of the vertical stabilizer tapering down to nothing near the aft edge of the turtle deck. I think this was a nice astetic improvement on the series 7 and it makes it much easier to lay the fabric in that compound curved area just forward of the vertical stabilizer and minimize a bunch of fabric wrinkles. There are a number of threads on the forum that describe what others have done. The picture below shows the 1/2" diameter chrome moly tube I added. Although it's a personal thing on wether you like the looks or not, it helped a lot when covering with fabric. A few other things to consider as series 7 upgrades: If your kit came with a plastic header tank like mine did throw it away and get an aluminum one from Kitfox. Almost everyone has leakage problems eventually with the plastic tank. Also consider the elevator spring assist kit which neutralizes back pressure on the stick. Kitfox also sells new lower force springs for the carburetor throttle return which neutralizes throttle creep. If you don't have an oil cooler and thermostat you might consider adding them. Kitfox sells both. Add voltage spike diodes to the master and starter solenoids.
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