I think you should save your money for more paint. Its a gun, its supposed to go bang when you shoot it. Ive tested so many bolts over the years, and most don't actually do anything better over the stock bolt. In fact, some of the bolts restricted air flow, and made the mini perform worse. All of them however needed so much fine tuning with settings and a different spring, just to make it work like stock, that it wasn't worth the price.
i know a new shiney seems a good idea, but its often just an aesthetic choice rather than actually functional.