I had an Uno turbo ie many years ago that produced something like 140 hp - an amazing little car and the standard engine management just coped with the extra boost with no problems - other than disconnecting the boost limiter switch. The only problem that I had was with the high temperature hose from the turbo to the manifold having to be replaced every six months or so - could tell when it was starting to go by hearing a whistle. The gearbox gave zero problems but, of course, the strain on the transmission was self limited by wheelspin - could spin the front wheels at 4000 rpm in third gear, for instance.
Lovely job, by the way, this is what the X1/9 should have been all along.