hi hi kylim8
If u want to mod your s15 to 450hp then u only need to change all your eng head set to
HKS step 3,
Greddy T67,25g turbo and
Power Fc ecu.
Hope this list can give u some ideal
sorry tat i bring out this Q tat prehaps have been mention ages ago...
but i still don understand.. lets say... if i get a 2nd hand rx-7...
why i need 2 rebuild the engine??