I'm pretty sure the SR20 swap isn't smog legal here in California so you may want to check the laws in Texas if you want to avoid a possible hassle. I'm pretty sure you'll need the engine complete with harness and computer like most swaps. It might be easier to swap a ka24De or do the KA turbo but the SR makes some awesome power when set up right. Check out nicoclub and nissanforums, they're pretty active. I like to read hybridz.org they have a ton of info on engine swaps in Z cars but might have something to help with your S13. good luck!