does anyone know the difference between 86-88 and 99-91 rx7 intake systems?

the reason why i ask is because, i wanted to buy HKS's "power suction" kit for my 88 turbo but the years it specifies are for 90-91 cars.... can it fit on an 88 year?

 

the AFM on S4's are different than the S5's. if you're buying the HKS, you'll need the AFM adapter if yours is an S4.