Exhaust leak?

[Miguel92.3000GT]

Alright guys, I just drove my car after changing out the vss and head gaskets. The car accelerates pretty rough but when it reaches around 3k the car accelerates great. And the exhaust is louder than I remember. Can this be caused by an exhaust leak?

[stealthee]

Is your VICs motor plugged in?

[Miguel92.3000GT]

Yeah its plugged in. Although my younger brother is sort of a trouble maker and I found him taking the VIC motor apart one day after coming home from work. Im pretty sure I put it back correctly though. The car also smokes from the downpipe flange after I drive it for a while. Could this be a problem?