On a STD engine to push 400 out of a t34 is asking a little too much and they don't like holding 2.2 bar at high revs, I spike of 2.2 is good but they are Time bombs at that boost iirc mike rain bird done a few t34's pushing over 400 bhp

The .48 is better for a road car IMHO though loose 20 or so hp for more response