You did not mention what computer you have or your injector size. I am guessing 24lb, and the x3z?
My opinion is that when an aftermarket MAF and larger than stock (based on the computer used) injectors are used, a tune will be beneficial. Especially if the CID of the motor has changed with a 351w conversion or a stroker.
I just started making some tuning adjustments with my TwEECer this weekend, so I do not have a perfect tune yet. Here is what I think though.
The TwEECer is the best thing to happen to the EEC-IV, since MAF
Basically, all I have changed is the fuel injector settings, CID, MAF transfer, and disabled the emissions settings that have been removed from the car.
The car would only idle steady before at 950rpm. Now I have it set at 650rpm.
The improvement it part throttle response is incredible.
I still have to play with the fuel and ignition timing, as well as some cold start fuel settings.
If you are willing to take the time to learn how the EEC works, then an aftermarket programmer is perfrect for you. If you the kind of person who just wants to get in the car, and drive it then maybe you should keep taking it to a tuner.
Be honest with yourself on this, and realize that there is a stiff learning curve, when digging into the factory computer.
Boost would probably be ok with that combo, if you keep it within reason. The 190lph may be the limiting factor on how much boost you can run.
Feel free to keep asking questions, that is why we all come here.
jason