I own a 1996 Honda Civic with a 1.5L non-VTEC engine.  Would like to improve on the bhp and torque short of changing engines, turbo or supercharging.  Have started modifications by changing my stock intake manifold with a 1600 VTEC intake manifold.  Also changed my stock airfilter as well as added a Spoon exhaust.  Am planning to change my stock headers with a 4-2-1 headers.  Someone suggested to shave, port and polish my engine but to what extent? Would like to ask what else can I modify with regards to my engine?  Are there aftermarket parts that I can install?  If possible please be very specific.  Thanks a lot. really appreciate it.  

its not a race car dont wasn't your money, but a better platform and work off of that  

Consult a professional with a respectable reputation. But to me, it seems that for all the money, time and work you would invest into getting that engine into shape performance, you could just opt for a full powerplant swap instead and be better off in the long run.