Speed Density Questions knowledgable tuners needed

[William Bowers]

I recently purchased an 88 LX 5.0 from a transplanted Yankee. He had to sell it cuz his homeowners association wouldn't let him have more than 2 cars in his yard.1 owner bone stock, and in very good condition(interior brand new,everything works nothing broken). 1800 dollars seemed cheap to me!It runs and drives fine but I would like a little more power/sound.I intend to add :shorty headers,x-pipe,Flowmasters,Pulleys,phenolic spacer,Remove smog pump and intake silencer,3.73 gears,adj clutch cable,Cold air intake,new ignition,plugs,wires,coil,bigger fuel pump and pressure regulator,and a 70 mm throttle body. I do not want to open the engine in any way(yet) cuz it runs really goood and only has 88,000 miles.My question is the speed density system, I keep hearing that it needs to be changed over to mass air. WHY? It runs really good and I can't seem to justify the expense.Will it not work with the add ons I am considering.The only other things I might ever do to it is change the heads and the cam. I don't want to go to bigger injectors or change over to mass air. It is only a street driven car(I only drag race import bikes). And besides if I get the bug I have a 4 cyl body and 460/C6 sitting in the corner just waiting for me to get the time to mess with. I don't want to affect the streetability of the car cuz I don't intend to take it to the track anyway.

Is there anything else I can do to improve the performance,besides those I listed ( and that don't require opening the engine)and are any of them (that I have already chosen)not worth the trouble.Thank you in advance.