This is true but not the whole story: if you shoot a contrasty scene at 400 and develop normally (for 3200), the highlights will be crimped by the shoulder of the film and you will only get good contrast in the shadows & midtones, maybe up to about Zone VI. The density that the brightest highlights should be at (to maintain a linear response) is past the film's D-max. The end result is that the print looks duller because of the reduced highlight contrast; it will lack sparkle and is a similar look to using a compensating developer.
In order to prevent the highlight destruction, one typically reduces development when over-exposing in order to ensure that you don't get much of your image up on the film's shoulder and therefore mushed. The global reduction in contrast (which can be rectified by printing a grade or two harder) is preferable (for most people) to keeping full shadow/midtone contrast and losing most of the highlight contrast through what is effectively an overdevelopment for that EI.
Of course if you shoot a scene of little dynamic range (4 stops), there will be no problem with the extra development. But such a narrow scene doesn't need the extra exposure either...
Anyway, I stand by my original suggestion of shooting at 800-1200 and developing for 1600. D3200 looks foggier than it really is, if that makes sense. There's an image hiding in there somewhere!
I thank you for your effort in response but may i ask if you could help me understand what you are saying by telling me what the shoulder of the film is, d-max and well quite frankly even then i would still be confused.