Here are some truths about what we were talking about:

1. This car is pretty damn well balanced from the factory in terms of power, feel, handling. The Z is not about being the fastest. It never was. It is about a balanced, affordable, great looking sports car.

2. Nissan wanted the car to be within a certain budget, so obviously compromises needed to be made. Engine internals, etc.

3. FI will significantly increase your chance of engine failure. To do FI properly, you essentialy need to build an entirely new engine. To balance that power, you will need to practically build a whole new car.

4. NA mods are a poor value, but do change the subjective feel of the engine by altering the shape of the power and torque curves. There is a power gain, but it is small unless you want to start spending MAJOR $$$$, but then, basically, you are building a whole new engine....just like FI!!!!!!

5. Everyone will think that what they have done to their car is the best way to go so asking opinions on this will give you more information than you can make sense of.

To help you decide what to do, ask the following questions

1. How important is reliability. Are you the type that would get really frustrated or bummed out if something went wrong from time to time? If you are, forget FI.

2. How deep are your pockets? To build a GOOD, BALANCED, FI vehicle will cost you $35,000 on top of the price of the car....and it will still not have factory reliability

3. Is the stock Z really fast enough for you? If yes, some NA mods can definitely make the car more enjoyable just by changing the engine's character, if not really increasing performance by much (45+WHP). If you are looking for real performance increases, FI is the only way to go (nitrous excluded).

4. BMW's design philosophy is "build a great engine, then make it the weakest part of the car." A moderately powerful car with oustanding handling, steering, braking, shifting and grip will be much more enjoyable overall than a car with a monster motor that overpowers all the car's other
mechanical components.

All just food for thought. Getting back to your original point, NA mods will give you a different feel, but little real performance gain. Even 35-45hp will only take about 0.3sec of any of your times.