caps won't make a difference on how the image look unless they're on sync. They'll just keep out extra voltage. What're you wiring this into, a scart tv? A scart to component adapter?
By the way all genesis/megadrive systems I've come across have jailbar like interference in the rgb (and s-video when you add that modification). There's also a funky rainbow effect that goes on from the system that doesn't show up on tvs. I'm currently working on a way to clean up the image but it's really complicated. I basically wired a cxa1645 circuit into the system and here's the difference:
The non portablizer! Specializing in....Video quality?