I am currently at 70k power and aim for 80-90k

How much power can I get with 20k coupons to spend?

and whats the best thing to buy for it?

Most of my charm levels are at 5 excluding 2 which are 4 and 6

My refines are all 7 mostly excluding 7 of them, 5 of them being 6 and 3 being 8.

Have anbu clothing, wild west, 70k power clothing.

Have maxed out ninja exam stuff.

Phase 6 of mt myoboku

What can i spend on to improve power the most currently?