Difference between seq and non-seq turbos?
 

Can anyone provide me w/some info?

Also, can you tell me if having turbos burn a little bit of smoke under full boost is an real issue that should be addressed before continued driving?

The smoking means that the turbos have bad oil seals with will require a rebuild or a new set.

The sequential turbos spool faster but are more complicated and difficult to maintain. The non sequential mod make them work symotaniously so instead of on boosting the other, they both work at the same time. It is more simple but a little more laggy.