We never see why Curto was a rat and had he not died he probably would have gotten Tony gone for life. Funny because in the scene immediately following Curto passing away in the FBI car Tony exclaims "Can't I catch a fuckin' break!?!?!" Little did he know he caught a huge one. Pussy didn't' really give the Feds much and him and Jimmy got killed before they could give the FEDS anything useful. Eugene we don't know either, he was gone before he could do any real damage. Before the timeline of the show started that "Febby" Petrulio did a ton of damage and got the boss DeMeo locked up for life. But it looks like at the end of the show Carlo was going to end Tony's run....Tony probably made his decision to rat that much easier since he was such an asshole to Carlo on a few occasions. Screaming at him in the car about Vito bringing in 3x what he did in the construction rackets for instance. Carl didn't appreciate that talking down to.