I see we agree here..
I mean you put speakers in your car that need 90 watts
stock head unit 30 watts or so
equals a overload that at somepoint most likely will fry it..
U are mis-informed my friend.
So ur new speakers can take 90 watts...OK
The stock head unit can only push out 30 watts....great
Where's the overload?? There is none. Your speakers are just underpowered. The radio is not affected, the radio is strictly limited to the 30 watt output .
Now if the OEM speaker has a 4 ohm impedance and u replaced it with a 2 ohm impedance speakers, then u have a problem. Theres your overload.