hi there , been told it might upset the handling if you go lower
Sometimes we get "told" wrong things. The hard part is determining which is wrong and which is right.
It also depends on what's important to you. For some, it's all about "looks". For others it's what "performs" best. And of course there those that don't have a clue what they want and do stuff anyway.
For me and my Datsun 240z, it's only what performs best out on the track.
For a street car, you need to consider things like bumps, potholes, driveway ramps, speed bumps and the normal unevenness of the road. There's no point in bashing the underside of your car on small bumps.
It doesn't look cool nor does stopping in the middle of the Blvd.
Lowering the car also effects the camber, caster (not much) and toe. If you go too low this can't be trimmed out with a normal alignment.
A lower center of gravity is always a good thing. But, there is also a thing called "roll center". Quite often when a car sits too low, the roll center is compromised and forces the car to actually have more body roll. Not a good thing.
I want to mention "droop steer" and "bump steer", but that will just add confusion to an already complex subject.
Spring stiffness is part of the equation here. Others have found out the hard way that if you don't increase the spring rate, the car will bottom out to easily.
And there are things like anti-roll bars. Sway-bars as some call them, help keep the car flat in a turn. They don't alter the ride height, but they usually add to a stiff, bumpy ride.
An entire thread can be devoted to shocks alone. Shocks need to be matched to the travel and ride height of the car. The damping also needs to be considered. Shocks are a two-way damper with bound and re-bound. The manufacturer has pre-set both of these. Some really expensive racing shocks are user adjustable. Just changing shocks can make a big difference.
So, why didn't I mention any specifics?
Each make and model of car is unique. The is no one best rule that fit's all cars equally. Generally, lowering a car one inch (24 mm) is safe in all respects.
Please keep in mind that to change any one thing of the suspension will effect
all other parts of the suspension. The original designer had a hard job at making what he/she thought the best compromise would be for most people and most driving styles/habits.
There are plenty of good books on suspension theory and design. For cars that are popular enough, there are books devoted to that specific car. Yes, I own a few, but I don't claim to understand what I read.