Umm...well, if u want to lower the car more than springs can do.....what was the question again?

What are you trying to do?  Drop (how much?), go faster, reduce roll, increase compliance or stiffness?  More information needed...

The question whether to lower the suspension in a car is primarily the issue...

Most people do this for aesthetic reasons, not understanding that the geometry of the suspension is thus altered... furthermore the use of spacers to get the wheels "looking better", or to use wider tires and rims than the manufacturer recommended.

In my opinion lowering the vehicle with lowering springs (retaining the original shock absorbers) is completely wrong and in some cases may prove even dangerous... the reason being that the stock shock absorber might not work properly if it is somewhat compressed, because the remaining length might not have enough bump/rebound and even might bottom out.

Coilovers are better in this respect, because they take into consideration the lowering and pre tension of the coil, at same time bump and rebound adjustments make it easier to match with the weight and type of roads you are going to use the vehicle, plus the variety of spring tensions might make it compatible with your vehicle.

There is a very good reason for a manufacturer to choose the height of the suspension, spring tension, and bump/rebound... this is because road vehicles are supposed to drive on roads, and roads have a variety of surface and quality of tarmac... furthermore there must be a level of comfort.

Track day cars, will usually be driven only on track, and they can be lowered quite a bit, and the srping tensions can be very high... such a vehicle although very competent and safe on the track, it is by no means safe on the road, because the road has a vastly greater variability in quality, ie bumps, potholes, unevenness etc...

I went into these variables very briefly,... my general recommendation to you is firstly,...to leave the car alone and don't mess with it..., secondly if you do want to mess with it, make sure you have a good understanding of what i explained to you above and then get yourself coilovers from a REPUTABLE brand (stay away from cheap Chinese brands), that most users of your vehicle seem to like and have come to an agreement what adjustments should be made...

When you have have installed them, take your time to relearn your car, preferably in a safe environment such as a race track (not the oval type)... make notes of what you like and dislike, and then proceed into final adjustments...

On the matter of body roll... it is inherent in the car's design (suspension geometry)... reducing body roll, would not make your car have better grip, nor will it make your car more agile... it will only affect how you feel about the car under these conditions, and in many cases it might make you feel more confident than you should... your car would be less gradual and more sudden...

Sport cars are designed from the beginning to have the suspension characteristics they have, one cannot transform a day to day saloon car into a sport car...

Hope you found these few points helpful, and good luck with your lowering project!! 

I have to kindly insist on point 4, that the lateral inertia of the car going through a sharp corner, is identical whatever the suspension height, or the body roll... grip has to do with the ability of the tires to remain in contact with the tarmac, and assuming the inertia is the same (speed times mass)... the car that maintains the maximum tire to tarmac contact is the car with the better grip...

In lowered (only with lowering springs) cars shocks do not work optimum, their bump/rebound characteristics are altered for the worse... which in fact a lowered car might have LESS grip in a corner... because the (now compressed) shock absorber might not be able to apply the same pressure on the wheel/tire..

Same applies to severe braking, you may have a more sudden dip (although shallower) because of diminished bump, of front shocks, and you may also experience tail lightness because of diminished rebound on rear wheels...

The body roll is a parameter that is inherent and i would also say desirable in a street car, (except for comfort) to make the driver (everyday driver) aware of the increased speed or bend sharpness...

I have managed only very slight better lap times in similar cars with only differences the suspension height, (with the same shock absorbers), and that was only because of a little more confidence provided from the lowered car, and not in actuality of better grip...

I have very little knowledge of American cars, but surely the same applies to all manufacturers,... that, considerable thought is put into the suspension designs because normal people are going to drive them, and not only race drivers.

On the other hand if you are going to drive within the legal speed limits and carefully... you may may go lower only with springs...

The best though is to go coilovers.

Having frequented tracks, and owning a track day car, i must insist on my points because i have explained adequately, that i am speaking about the SAME car with STOCK shocks (and of course the same size rims and type of tyres)... the lowered car MIGHT handle WORSE...

I think this is simple enough...

Now on the other points you make about suspension geometry might be valid, but the inherent geometry of cars designed to be street cars, can only be MINIMALLY altered (talking about height)... and is not measured in many inches... only a few,... if only one or two maximum, and ALWAYS in conjuction with the appropriate coils and shock absorbers that will handle the altered height.

In any event i hope people that read this and want to "pimp their rides" do so carefully...

Having frequented tracks, and owning a track day car, i must insist on my points because i have explained adequately, that i am speaking about the SAME car with STOCK shocks (and of course the same size rims and type of tyres)... the lowered car MIGHT handle WORSE...

I think this is simple enough...

Now on the other points you make about suspension geometry might be valid, but the inherent geometry of cars designed to be street cars, can only be MINIMALLY altered (talking about height)... and is not measured in many inches... only a few,... if only one or two maximum, and ALWAYS in conjuction with the appropriate coils and shock absorbers that will handle the altered height.

In any event i hope people that read this and want to "pimp their rides" do so carefully...

What's a street car?  A Camry, Corvette or Porsche Boxster??  The last two come with variants w/ 1-1.5" drops from the factory using the same suspension geometry.  Others like TRD will sell lowering springs w/ full factory warranty and support.  W/ proper adjustability in the suspension in question, proper alignment can be preserved after modding.  Even then, aftermarket lower control arms, and camberplates/tophats can deal w/ any issues.  Roll-center adjusters fix raised roll centers from lowered suspensions, proper coilover design and top hats also compensate for preserving rebound and compression stroke is designed right. 

So if you know what you are doing, you CAN lower a car and improve performance.  Manufacturers and race teams do this, it's not snake oil but like everything is relative. 

But yes, done wrong, most people w/ incomplete knowledge can/will make their car handle worse, slower, more dangerously.  Done right however, you can improve speed, feel and even ride comfort at the same time.  My friends track Integra rides like it's on rails around corners but feels better than most Cadillacs just cruising on the street.  That car is so dialed in it's ridiculous.

Might want to look at what 'M' sport options are available for your car.  You don't have to buy a complete M to get the M suspension package.