well i just had my car flash tuned its an auto au1 xr8 with full exhuast and G&D cold air intake. before tune it pulled 120rwkw and after 141.7rwkw.

what would i need to do to take it up to 200rwkw and around 500-600nm i do not want to go forced induction.

New internals etc

Internals will be fine at 200rwkw.

You want to change to a mild cam, like the Crane 2030/2031.

You will need to change valvesprings/retainers/locks, and pushrods. I would recommend you change to roller rockers as well.

Should get you very close to 200rwkw, and high 13 second passes. A higher RPM stall converter would help heaps as well.

Next step would be changing heads, and inlet manifold...or porting the stock heads and inlet manifold.

set of underdrives for it and a throttle body upgrade and some hi flow injectors should help you out but if u get the injectors you will need to retune it as the tune you have suits the injectors you are running at the moment