How do you know when the spring in your DV is not strong enough?

A complete balancing act - the red spring in the Forge tuning kit is supposed to be good for tons of pressure but on my car which is running 17ish psi doesn't hold boost in 4th or 5th.

It is a question of trying combinations and seeing what happens.

Try putting a strong spring in, if when you rev the car hard then change gear you get a big pause before the power comes back in the DV is not working properly.

If you don't feel the difference try driving with an obviously weak spring and see how that feels (from what I hear it is not going to cause any damage as long as you don't drive for too long).

Greg