just please make sure your sarm's are from sarms1.. very important!
also for pct you don't need much at all. GW isn't suppressive and S4 for just 8 weeks is not going to suppress you much.. a bottle of hcgenerate will work just fine for pct
SARMS are only minimally suppressive of natural testosterone production so all that is needed as a mini PCT after a cycle of SARMS is a good natural testosterone booster like HCGenerate ES from n2bm.com.
Like this -
Weeks 1 - 8
cardarine 20mg/day
S4 50mg/day
Weeks 9 - 12
HCGenerate ES 5 capsules/day
On week 13 you are safe to start your next cycle of SARMS.
If I were you, I would add ostarine to the stack to have the complete triple stack. Also, the ostarine from sarms1 is quite cheap - 80 bucks for a 2 month supply. It would enhance the cycle pretty well for quite a low additional investment.
As for PCT - a good test booster like HCGenerate is more than enough.