the only things that will add noticible power is turbo or changed headers and the whole exhaust piping, you can buy all that on ebay, but have to be very careful, you get what you pay.
to add some noise just buy a muffler (which will not add power without bigger piping and headers)or buy a cheap short ram intake, i have it, and love it, it gives a nice deep sound, some cai piping from ebay are sometimes not bend for proper fit.
Just...shut...up.
A
HEADER will give you maybe 4 horsepower as well as a full exhaust system. Like said above, I/H/E will net you maybe 5 horsepower on the D16Y8. The only way to get good power is by turbocharging/supercharging/nitrous/building engine, any of those will net you noticeable gains. An intake is an intake is an intake. They are all filters attached to a pipe. Just buy a K&N filter to put on the end of the pipe. To the OP if I were you I'd save up and buy a greddy turbo kit and call it a day.