None of the upgrades are "needed", but I do recommend them all. The Redline is comfortable and convenient. Makes board changes much easier--no more counting flashes. The Boss bolt is quieter, has less kick and gentler on paint than the stock bolt. The stock feedneck is a good feedneck for most. The only drawback for me (and some others I am sure) is the slit on the back of it. I tend to pull my barrel condom off the barrel and leave it hanging from the feedneck/hopper. Sometimes the condom cord gets wedged in the feedneck split and stops the balls from feeding. The Nano (and many other feednecks) solves this problem.
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