i would say it has to do with the arteries in your arm and neck. since your heart may beat harder than usual increasing the systolic pressure. just a guess. i could be way off though.
I just bought a kicker 500 rms mono amp they kicker place said it would power it but they also told me some other amps like 550x2 and 750x1 i also bought a quatum audio 800 mono amp.
amp,2 12" kicker cvr 800 watts subs? cuz at the auto shop there gonna charge me 250 to install and for the wiring kit and there charging to much for the kit so i wanna buy my own?