Mainly tuning because of the compression ratio on your B16 head. A lot of people think turbo VTEC introduces a lot of problems, and in reality it does, but it all depends on the tune.

Tuning is key with DOHC VTEC engines, and since the B18B has a lower compression ratio and no VTEC there is more room for 'error' in the tune (as far as A/F goes)