Fuel pump,injectors ,coils,computer(All to be done at the same time due to tune)
Good time then to change oil pump and water pump, timing belt , bearings and bolts if you have not done.
Then suspension and brakes.
After you have spent 10K you will want to do turbo upgrade with a/m manifold.
If you have read this far you are a mod-do-holic and not even 1000hp will cure you
How much money do you want to spend?