Base Z + Upgrades vs Sport Package? Advice needed

[mook]

Value wise, would you recommend buying a base Z and upgrading the suspension or going for the sport package?
This is not for track use, just street entertainment. Usually, I am an off the shelf car buyer but my last car was upgraded by the previous owner and I loved it. I like to drift and also prefer less body roll, crisp turn in and don't mind a moderately harsh ride.
Definitely need an LSD.
Don't want the syncro rev thing.
I am not mechanically adept so would have a shop install everything. Never done this to a car, so this makes me nervous.

I suppose, the options are 1) base Z + nismo parts (haven't seen those in the catalog, yet) 2) base Z + aftermarket 3) sport package

Would someone be kind enough to recommend components and give general thoughts. Component, installation prices and all type of advice is highly appreciated.

On a side note, I am thinking that smaller diameter base wheels give better accelleration (provided you can hookup the same) + less weight + easier to slide around? Comments?