Since I fixed the vacuum leaks, it idles fine. A bit high, but it idles at a solid 1k. Although, it's a bit rough at the higher RPMS. If I'm going 60mph-80mph, it's kinda rough and shaky.

Oh, something else I just thought of... This exhaust has a hollowed catalytic converter. Is it possible that the catalytic converter on the stock exhaust was holding back a lot of the smoke, and It just made the problem less visible before the switch?