I want very minimal throttle slack but i already adjusted it at the tightest spot (bar turned all the way to the right).
If i make it any tighter the throttle doesn't snap back but it does roll off slowly. Any suggestions? Can i tighten it more even though the throttle doesn't snap back?
The whole point of the sprung return 2 cable system is auto throttle close upon release of grip plus back up of the second cable.
With some slack, the cables will bind.
The trick is to get as close as you can without losing a nice quick throttle close by release of hand.
Sometimes a cable routing change will help, or getting the routing correct after a bad reroute.
Sometimes a bit of cable lube will help.
It's always more of an issue at steering lock.
Personally, I set mine up for nice closing action through most of the bar sweep, but will accept some degree of binding at full lock IF that is what I must do to get minimal slack through most of the sweep.
Keep in mind that what is NOT OK, is to have so much binding at full lock that you can't easily close the throttle by the return cable.