Coffee Appreciation

Right, need some help coffee fiends...

Tentatively thinking of PID modding my Silvia to address the massive inconsistencies in shots that are coming through. I can pull two shots with the same grind and dose and get two completely different espressos which suggests that despite my best efforts at temperature surfing, the boiler is still overshooting the temperature with each pull. Does anyone have any experience of this/recommendations/good reason for me to not look into it further?

What grinder are you using? Also have you used scales to chek that your dose is as consistent as you think it is?