Upgrade your AEG's fps to 380 to 410fps. It is highly recommended to upgrade plastic bushings and spring guide to metal bushings and spring guide with this product. Also, it would be wise to upgrade plastic pistons to polycarbonate piston; plastic piston heads to duracon piston heads; and standard gears to reinforced steel gears. Finally for best results a battery upgrade is also recommended.
I've been modifying gear boxes for some time now, and I can honestly say that Promethius brand upgrade parts are definitely worth the money. The longevity of this spring is something to be admired, especially when coupled with a ball-bearing metal spring guide and polymer piston. I would recommend this spring to anyone who is looking for a performance boost, while still maintaining a stable system. I DEFINITELY recommend using upgraded gears before installing this spring. If your gears are old or can't pull an M120, it's only going to cause problems. Overall, this is a good buy.
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