There could be a combination of things at play here. Boost leak, plugs, wires, o2 sensor, too much hot air forced down the chambers (too much oil in the stock I/C), and so on. It's not really a clean cut answer to your question.
17 seconds is not good for a turbo DSM, even for an auto which rates close to a manual in times.
Did you get FP to rebuild the turbo into a Big28? If so, your car is dead slow. Even at 12psi, there is a big difference between the t28 and big28.

No one has suggested it yet, so I will suggest for you to do the normal stuff such as a boost leak test, replace plugs and wires, clean I/C to include the piping, change your oil, PCV valve (could cause a slight increase in positive pressure in the head), and so on.