Eibach Pro-Kit Springs (ZZZZZ)
Japanese production cars generally leave too much wheel well gap for my tastes. Even the NSX has a little too much wheel well gap for me. Seems only the European manufacturers care about how the wheel well gap appears. The Eibach's not only improve the looks of the Z, but also improve the handling characteristics of the car. These actually only lower the Z .75" which is not much at all. The spring rates are a bit stiffer than stock springs, but is very streetable. I would recommend these for Z car owners; however, be prepared to replace your shocks if they are more than a few years old on a twinturbo or if you have a non turbo. (The shocks on the twinturbo can take it; however, those on the non turbo can not.) Since you have the suspension out, it is a good idea to replace your shocks to save labor costs. These generally run $250ish for a set from and come with a limited lifetime warranty. They are available from Stillen, SGP and many other automotive shops.
Stillen Adjustable A-Arms: (ZZZ)
These allow the camber to adjust on the front wheels of a 300ZX if your car is lowered or has negative camber for some reason. While these are highly expensive, the cost can be justified when you don't prematurely wear out the inner tread on a tire and prevent any damage to your cars body. I've almost had it happen before I purchased these. I had lowered the car which threw the camber even more out of place. While the tire appeared to be wearing normally with a quick glance, closer inspection showed that the extreme inner edge of the tire had worn down to the chord. Luckily I caught this in time and purchased a set of these A-Arms. This has saved me in tire replacement costs and are well worth the $400 per set from Stillen.
Tokico Illumina Adjustable Shocks: (ZZZZ)
I had these on my non turbo car after I replaced the springs on that car with Eibachs. The shocks were just too soft for me so I decided to go with something a little bit stiffer. (I like really really stiff racecar suspension set ups.) Unfortunately, the Tokicos were not as stiff as I thought they'd be. While they were a significant improvement over my stock shocks, I would probably try KYB shocks next time if I wanted to go aftermarket again. Still, these were a great value at a little over $100 each from Stillen. The five way adjustability of these also makes the ride a lot more fun. Setting 1 (softest) felt softer than stock non turbo shocks and setting 5 (stiffest) felt about equal to "Sport" on the stock twin turbo adjustable shocks. For those that don't enjoy that pure racecar extra stiff shock feel, these are the perfect shocks for you, and at an excellent price too.