the installer should take care of all tuning. you shouldn't have to change/adjust anything on the amp. but take non-blurry pics of the amp settings after you get the car back and we can evaluate/review.
you should take care with the volume control. in the end, your use of the volume control will determine if you damage your gear. note that you can only be so loud with a given system/investment.
post pics of the end results (we like pics showing wiring routing/connections). ask the installer to take pics during install (this will keep him honest).
the Kenwood has built-in high pass filters for the speakers - make sure these are turned on (will be set around 80Hz-100Hz) depending on the sub amp low pass filter. you do have some tuning ability in the HU, but as a general rule - an eq should be used to cut frequency peaks, not boost. boosting increases change for clipping (by causing clipping at a lower HU volume).
your stock speakers should sound much better on the Kenwood HU (compared to stock HU) but won't sound great. if you hear distortion in the speakers, that's inherent with any head unit amplifier above 1/2 volume or so. you shouldn't need to boost any bass EQ settings since you have subs now.
when you get it installed, read the manual for the HU control/features/setting. if you have any specific questions on HU settings, ask.
