larger exhaust housing on Gtir so will support a bit more power

Pulsar has top feed low impedance injectors and are larger than the S/RPS13 and S14 ones (S15 has 480cc injectors)
They use the SAME pistons (the compression ratio difference comes from the larger combution chamber)
Pulsar has a little stronger rods
Pulsar has 19mm rod bearings with 360* oiling
Pulsar has different flywheel and clutch
Pulsar has higher capacity water pump
Pulsar has higher capacity oil pump
Pulsar has Larger valves
Pulsar has Larger combustion chamber
Pulsar has better valve pockets
Pulsar has larger flowing intake and exhaust ports
Pulsar hasQuad throttle bodies
Pulsar has solid lifters
Pulsar has larger head bolts
Pulsar has 20% stronger main bolts even though they are the same size/spec.

oh and the blocks are slightly different too

but yes the pistions are still made from choclate (just drop some forged bad boys in and youe laughing)

but you still have the gypo s14 engine