I cant believe you are asking about the z3 it comes with the 2006 SI... the thing sucks you have to buy a whole new ECU to even tune the dam thing right if you add headers, exhaust, intake, then you will actually lose power on that thing until the ECU is replaced or upgraded.. The Z3 also uses a throttle by wire system.... i say stay away from the Z .. stick with the A's
k20a : 220hp, 155 ft-lbs
k20a2: 200hp, 142 ft-lbs
k20a3: 160hp, 132 ft-lbs
k20z1: 210hp, 143 ft-lbs
k20z3: 197hp, 139 ft-lbs