It is true that a turbo or a swap to a V8 will give better, more reliable power.
However, if you feel like spending money on the N/A L6, then you can do some minor tuning things like: bigger throttle body, ram air intake, high performance ignition, headers, 2.25" to 2.5" exhaust system with performance muffler, K&N air filter, etc. All these things will make a difference, but won't be nearly as effective unless you throw something like bumping compression, going to a more radical camshaft, having the head ported, etc. into the mix. Keep in mind that you should add up the costs of doing these things and then compare the figure to a V8 swap. The $$$ difference may surprise you; that's why so many guys on this forum have gone to Turbo 280ZX engine swaps, Turbo Buick V6 swaps, and assorted V8 swaps. Use the search function to look up all the information on what you want, and most of all, welcome to the forum!!
Davy