if you want to stay w/ the KA and get more power you can do a cam upgrade as well. O and J performance have a good selection for the twin cams. and good prices as well.
O & J Performance
also check out these other links as well
http://www.240sxforums.com/forums/ka24de-t-ka24e/121482-ka24de-n-cam-upgrade-guide.html
http://www.240sxforums.com/forums/ka24de-t-ka24e/110091-ka24de-upgrade-guide.html
http://www.240sxforums.com/forums/ka24de-t-ka24e/104043-how-build-your-ka24de-de-t.html
O & J Performance
also check out these other links as well
http://www.240sxforums.com/forums/ka24de-t-ka24e/121482-ka24de-n-cam-upgrade-guide.html
http://www.240sxforums.com/forums/ka24de-t-ka24e/110091-ka24de-upgrade-guide.html
http://www.240sxforums.com/forums/ka24de-t-ka24e/104043-how-build-your-ka24de-de-t.html