Upgrade heavy spring (aka Gold Spring) to fit the Spyder paintball guns - and may also fit similar style paintball guns.
Mainly for security use - NOT FOR PAINTBALL GAME USE as this may push you over the allowed velocity limit on playing fields and also may result in paintballs bursting in your marker.
WARNING: the use of this heavy "red" spring does put more strain on your marker's internal mechanism and the installation / use of it is done entirely at your own risk. It may also void manufacturer's warranties if you have a newer marker, or damage valve housings on older markers.