found this on the internet thought I would share good write up.

Why do people lower their Z/G?
There are generally two functions that lowering a 350Z or G35 may accomplish:
Aesthetics: Some people like the look of a lowered Z. The Z comes pretty low from the factory, but another inch drop can make a huge difference the overall appearance of the car.
Performance: By lowering the car, you are also lowering the center of gravity. This will improve cornering and reduce body roll through turns.
How far can/should I lower my Z/G?
This of course has no definitive answers. The answer depends on many factors including:
Type of driving -
Suspenion setup -
Road quality - where will you be driving? Daily driving a slammed car is not easy and there are many road hazards to take into account.Even potholes can cause severe problems if your car is lowered to much. Driveway angles are the most common problem. Many driveways or parking lot entrances become impossible to navigate with a car that is extremely low.
Body kit? - If you have an aftermarket front bumper, lip, etc.., this will have an impact on how far you can or should lower your car. Aftermarket body parts are typically lower and/or longer than the OEM bumper
If the car is used as a daily (city) driver, what is a safe amount, if any, to lower my car?
The answer to that depends entirely on the road conditions in your area. Being a factory designed sports car, the vehicle's ride height is already the lowest that Nissan engineers felt was acceptable for the majority of roadways in the United States. Further lowering of the vehicle may cause the owner to run into some previously unexpected situations, such as: the inability to enter automatic car washes, scraping when entering/exiting driveways, scraping or inability to traverse speed bumps and so forth.
Each owner will have to make their own assessment of road/driving conditions in their area before lowering their Z/G.



Do I need to replace the struts?
If the spring rate is within approximately 10% of the factory springs, then strut replacement is not necessary. If the new spring rate exceeds the OEM spec by more than 10% then accelerated strut wear will occur. Rates much higher than stock will result in premature strut failure, excessively bouncy ride quality, and potentially unstable handling characteristics. If you are upgrading to a coilover system, strut replacement is not an issue.



How do I lower my Z/G?
To lower your Z or G in a safe and effective manner, you will need to purchase and install aftermarket suspension components. This can be as simple as a set of lowering springs or as involved as a full coilover suspension setup. These are the two recommended methods for the Z/G
Canā€™t I just cut the springs?
Though you will hear numerous reports to the contrary, cutting the factory coil springs is not a valid method for lowering you Z/G. Springs may appear simple in design, but fairly complex physics are at play. Cut springs can result in poor ride quality, unacceptable handling, accelerated strut wear, and even damage to suspension components. Anyone who tells you that cut springs are "just like" aftermarket lowering springs is a person who has never ridden in a vehicle that has been lowered with a quality suspension system.
Which are better: springs or coilovers?
The answer depends on what situations the vehicle will be exposed to. Under specific conditions, a well selected spring/strut combination can produce performance results equal to (or better than) a coilover setup. Coilovers shine with their adjustably, making them adaptable to varying street and track conditions. If you have no need for this level of adjustability, then lowering springs will suit you just fine.



AFFECTS
Will lowering my Z/G affect the VDC system?
Nismo uses disclaimers on their suspension parts, saying that they should not be used with VDC systems. However, no negative affects have been documented so far.
Will lowering my Z/G affect the ABS system?
No. Lowering your car will have no impact on the anti-lock braking system.
Will I need an alignment after lowering my car?
Yes. After any suspension components are replaced, a four wheel alignment should be performed. CAUTION: Misaligned rear suspension components can render your Z/G very unstable and dangerous to drive at speed. Drive cautiously until the suspension has been aligned
Will lowering my Z/G affect the ride quality?
If spring rates remain similar to stock, then so will the ride quality. Raising or lowering the spring rate will have corresponding effects on ride quality.
Will lowering my Z/G really improve the handling?
In general the answer is yes. Though vehicles that have been excessively lowered (or make use of an inappropriate spring rate) can experience a negative hit in the handling department.



OTHER CONSIDERATIONS
Do I need adjustable suspension arms when lowered?
The answer to this depends on how far you lower the car.
The front upper A-Arms are NOT adjustable, so any amount of lowering will increase camber. While this is good for handling, it is bad for tire wear. A 1" drop has shown to increase tire wear if the camber is not realigned. See Front A Arms
The rear suspension is toe/camber adjustable to an extent. With an excessive drop (anything over 1") you will most likely need aftermarket rear adjustable suspension components. See Rear Suspension Links

 

Actually when you lower a sports car that already has a low amount of suspension UP travel , you will hit the bump stops a lot faster than you normally would. Bouncing off the bump stops isn't really that fun.

The the shock/strut part , even of the springs have the same rate as stock , the struts will wear faster due to the change in piston placement in the strut.

 

thought this thread had usefull info instead i got useless

 

+1

 

What a waste of 5secs.

 

^^ +1

This is almost all common knowledge.