It wasn't a mistake to ask for opinions, but it WAS a mistake to be so incredibly vague.
So you have $1,600 to spend on your classic, you already have sub-OEM quality suspension and a loud exhaust.
If you want to get some good opinions on what to spend the money on, you need to give us more information.
What sort of performance would you like to get from the car?
-Autocross?
-Drag?
-Time Attack?
-Track Days?
-Daily Driver cruiser?
-Sound competition?
-OEM Showroom Stock?
I would assume that you're looking for opinions as to how $1,600 could best be spent to make your car faster in a straight line. Before you should even think about spending money on "go fast" parts, you should take a good assessment of your as to what needs to freshened up or replaced. B13's ain't exactly the newest cars on the roads, and as such I'm sure MANY parts need to be replaced.
My opinion? Spend the money on a tune up. Go get some new sway bar end links, new tie rod ends, new wheel bearings, new spark plugs, new plug wires, new distributor cap, rotor, and seal, new O2 sensors, new PCV valve, get an oil change, get a new fuel filter, get a new battery, clean up as many grounds as you can, fix any CELs, get a new clutch, get some body work done, new valve cover gasket, new brake pads, new brake rotors, new clutch cable, new clutch, new headlights, get a coolant/transmission flush, etc...