Anyone had/got a 2.0 twin turbo around a 1996 been mapped whats the gain on it, is it more responsive 

Is it running completely stock at the moment?  And is it running right? 

You can get a map to circa 315 bhp if a manual.  I found mine runs spot on at 300.  The main thing that really makes a difference is the primary boost you'll get.  It's much nicer to drive as I rarely get on to the secondary because you get up to speed so quick on the primary, like driving a diesel really with the low end torque.