For the FT991 change write_delay=0 and post_write_delay=2

https://github.com/Hamlib/Hamlib/issues/1163

rigs/yaesu/ft991.h

@@ -165,12 +165,12 @@
 /* Delay between bytes sent to FT-991
  * Should not exceed value set in CAT TOT menu (rig default is 10 mSec)
  */
-#define FT991_WRITE_DELAY                    2
+#define FT991_WRITE_DELAY                    0
 
 
 /* Delay sequential fast writes */
 
-#define FT991_POST_WRITE_DELAY               0
+#define FT991_POST_WRITE_DELAY               2
 
 typedef struct
 {