What are the advantages or disadvantages in swapping out my fuel pump on my 86 rx7 na, midly street ported to a TII fuel pump?

 

No advantage. Stick with the NA FC pump.

 

mine is faulty, the gas light comes on too late and I have ran out of gas several times. Since I was going to swap it out I thought I should upgrade to s4 t2 or fd fuel pump assembly?If not, why?

 

From what I've read you don't need to upgrade to a bigger fuel pump if your running all stock components. When you get bigger injector and start messing with fuel upgrades is when you want to get a fuel pump that puts out more fuel. As for the gas light coming on too late it can be the floater in the gas tank isn't working correctly anymore or the gas gauge isn't working anymore either... it also can be other things but those are two I know of.

 

I plan on adding a CAI and HI-6S with 2 LX91 coils wired in parallel and Koyo radiator.

 

OK, first, just pay more attention to your fuel gauge. Second, carry an extra gallon of fuel in the car. I actually have to do this in my Insight as the fuel economy is so high I can drive 100 miles or so with the low fuel light on and nothing showing on the gauge.

If all you are doing is swapping the low level sender, then you can just swap that individual component. Leave your stock pump alone. The stock pump flows more then enough for your NA, which runs rich already from the factory. A TII pump won't do much of anything other then raise fuel pressure a little and make the car richer. That will just waste fuel and cost power.

Don't bother with the HI-6 and LX91 coils. Your stock ignition system is fine.

A true CAI is a good idea, as is the radiator if yours is in need of replacement.