Assuming your talking about acceleration. Go with an AEM cold air intake. They run for about $200 brand new which is a lil steep compared 2 the ebay china made products, but the aem will keep you street legal (Come's with CARB #'s on intake) and comes with a K&N filter that can be cleaned and reused for the life of your car. DC headers will also give you some much needed torq for that 1.6 liter single slam motor and will keep you street legal (has carb #'s also) Ceramic coated DC headers new will run you about $299. Both of these mods combined should be good for about 10whp. Check out craigslist.org or recycler.com and you might be able 2 find them used for about half the price! hope this helps.