on my capri i had gaz coilovers with 250lb springs with 7 inch wide wheels.
with 4 pot brembo brakes and 300mm discs, and a rear 253mm disc conversion
stopped and cornered like something completly different...
the loud bang is the spring moving in the spring cup. did you re-fit the rubber hose like things back on to the springs? i left these off my capri first time and i soon put them back on.
hope that helps.