Take a look at some of my Mods, and the Mods that are planned. There isn't a lot you can do Engine wise to the KA but it helps a lot. Your basic setup for 170-180rwhp would be something along the following...
Intake System - Injen is a good choice
Exhaust System - 8 or so HP at the wheels with some of these systems
Underdrive Pulley - Not to noticeable but it will help rev faster
Camshafts - This will ad some upper end power and smooth out the power band. PDM-Racing has some good cams for the 240sx.
High Flow Cat - Your stock one is probably clogged
JWT ECU - This actually really helps the 240SX. Dyno results are 10hp/10tq through the power band on some dyno's ive seen.
Headers - Good mod, more throttle response.
All this should be about 190 at the flywheel, and possibly 170rwhp at the wheels. Stock is about 130-140rwhp. Want to be a little faster than the rest, consider the following...
ACT Clutch - Don't let the power fade out of the transmission.
Flywheel - Got mine for 320$ and think it helped along with my ACT Clutch. Revs are faster and it kicks in way faster.
Engine Rebuild - You can put Higher compression pistons in the KA for an extra 5% through the power band. You can even use the pistons off the 89-90 240sx to get a 11.1 compression ratio. Check out rich at this link <a href="http://www.fatman-racing.com/240-sx.com/RPB/gallery.htm" target='_blank'>http://www.fatman-racing.com/240-sx.com/RPB/gallery.htm</a>
Ingnition - Helps a little, the stock plugs on s13's can get old.
There is always more to do but I don't want to get down to that detail.
Lastly, Weight is a big helper if you can lose some off your 240sx. Its hard to do, but helpful.
With all this done im sure you would get closer to 14.6-14.7 1/4 times. So thats near 180rwhp in a 2750 pound car. Im about there <img src="#/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>