Since
I have one of the most upgraded Boxsters 986 in the world 
here is what I would recommend
That is highly debatable !
If you are on a budget
Spacers (get those wheels to fill the arches)
Short shift kit ebay, dirt cheap and sooo much better than OEM.. albeiti a bit more work when car is cold.****
Cheapest sport exhaust you can find on ebay/Amazone, if it is too loud, fit Db killer in rear pipes..
Cheapestt bluetooth hifi you can find
De snorkel
and you are good to go..
if you have some extra cash
then
new coils
Coilovers
18" rims
Good tyres
Better exhaust
Sport cats
Updated hood with glass rear window..
updated front and rear lights..
if any cash left
New fly wheel and clutch, plus IMS bearing and rear main seal
upgraded brakes
new brake lines/steel
Swaybars front and rear
new motor mounts and gearbox mounts, as you car is 20 years plus, and the ones that you have are most likely worn or soon dead..
Steering wheel hub extender
Better sport seats
List can continue, but I do not think that there is enough space here on the forum
Good luck