The best *overall* first mod IMO is exhaust. Better sound, looks way better, maybe a touch more performance. But 160 won't quite cover exhaust. 250 would do it.
For 160 I'd go with UD pulleys. 160 is just about exactly the right amount (assuming you do the install yourself), and they net you a decent amount of performance.
You could also look at maybe an upper intake spacer. They're about 100 bucks, and I swear I'll shoot you if you don't do the install yourself, that's how easy it is. You could use the left over 60 for some little nicknacks, maybe some billet door locks or AC knobs or something cool like that.