alright, i was looking on rx7.com and i saw the greddy oil catch can 9mm and 15mm. What is this for? Where does it go? Is it needed? Do I need it?
I have an s5 t2 I'm swapping in to my 88 gxl. I'm going to be getting the greddy intercooler kit from rx7store.net. Do I need this oil catch can?

 

oil catch cans are typically used in place of PCV valves, to provide a vent and catch for the crank case vapors and a minor amount of oil in them.

So, you only need the can if you do not have your PCV