Well figure the 1st place guy has his car totally done to the rules and you only have Azenis and bushings. 10 seconds is not too shabby if I might say so.

You can upgrade your shocks just for this year if you need them. Then maybe next year add on Ground Control coilovers to the Konis.

But most of the time you are understeering because you are carrying too much speed into the corner OR like your instructor said not being smooth on your inputs. Typical novice mistake which isn't too hard to fix. Just slow down a bit more before a turn and smoothly turn into the corner.