So I am looking at doing the silicone vacuum hose exchange on my car. Rx7 store has a kit with four different hjose sizes 3.5mm, 4mm, 6mm, and 8mm. I understand that some of these hoses are to replace things such as the windshield washer hoses and such.

Where I am confused is that on robrobinette's site he says that the only sizes you need are 4mm and 6mm. Are the 3.5mm from rx7store not the ones you use for the rats nest and such, so how reliable would it be to use 4mm as suggested on robrobinette's site?

 

I just did that recently and found that for good silicon hose you will pay about $100+ for the lengths recomened on the RX7store site so I ended up just getting mine from there. You will have some left overs.

yes Go with the 3.5 tighter fit less chance of leaks.

IMO the hoses from RX7 store are way better quality than those from a auto parts store. (they are more kink resistant.)