Ok I think one person ripping on him is enough.
To answer your question 450 hp reliably would require to fully build the ka, but for an sr this is what you would need and what I own. If you want more answers heres a good forum KA-t.org
again KA-t.org
-pistons and rods (cp, wiseco, je, eagle, etc)
-cams (HKS, Tomei, Jim Wolf<--I own those)
-springs dpending on cam size (ferrea, HKS, etc)
-intercooler obviously
-Intake Manifold (greddy is the most popular)
-injectors maybe 800cc?
-gt30 turbo look into garrett turbos
-tune (I have a apexi power fc)
http://zilvia.net/f/chat/361235-how-...-240-have.html
http://zilvia.net/f/tech-talk/429924...rs-thread.html
OH! and also search this has been covered hundreds of time, so google is your friend and don't post without searching or you will get flamed. There now nobody else needs to say it.
EDIT: just realized you want any engine
ls1: best performance all around, but a lot of money, modifications, pita
sr20: less reliable at 450hp, lots of aftermarket support, probably less money spent
thats all I'm doing, so search for about the other engines