What exactly comes with the SLP exhaust package on the SS? Is it just the lid and loudmouth exhaust?

 

You talking about when you get it from the factory? Well that's called "Dual-Dual" exhaust, which the factory rated horsepower jumps on the SS from 325 to 345, it does not come with a loudmouth muffler/catback. But they are somewhat the same exhaust, only difference is Loudmouth, hence its name, is pretty damn loud, the dual-dual is quieter.