Question Going from stock cooler to liquid cooling

Not trying to overclock will system gaming performance increase and better temps?
Depends, if your temps aren’t getting high enough to throttle performance then you won’t get any additional performance. You will get better temps but I don’t see the point. If you are gonna go for water cooling you should use it and overclock and actually get better performance.
It just depends on the CPU and whether you were limited due to temps. Better cooling will help the CPU boosting behaviour but again if you already have decent air cooling that might not be an issue. What are your current specs?