Yay! Nice to have another fellow Rodeo user on SOC!
Aside from the usual barrels, drop forwards and regulators there aren't many upgrades out there nowadays for the pre-2007 range of Spyders. That being said... Try PaintballGateway
for the CIP Assault Block and CIP Ice Pick Bolt (both are excellent upgrades I've used on my Rodeo), and CCM
do excellent clamping feednecks. I'm planning on using them on a majority of my markers so I'm upgrading as and when I can afford to.