now that i can see the graph it really does not look like it boost leak to me!
boost leak would result itself much sooner and in fact reduce your torque by quite a lot - not suddenly show up at 3000rpm.
the OE turbo has hit max PSI by where you show the peak of your torque curve.... and with a laeak i would have thought it would result in peak torque much later... unless a pipe split on you on the dyno.. but that would NOT result in a massive surge of torque\power..... as per the grpah you posted...
Here is a recent one of mine - it is not a direct comparison as mine is a hybrod turbo, but it has got 3 runs on there.... 2 higher power ones and one 'safe' map
the SDI;s generally have a nice high peak, and then a gradual slow slide down as the revs increase...
you got a clutch slip at all with that new unit or summit as that shape is really quite odd and abnormal imo!
Hope you get it sorted out tho as it should be pretty tasty once sorted correctly