Research first. Dont just buy something because people said so. Know what the part that you are looking to buy does and understand its true function. You will always be told that you cant go fast without spending a lot of money. To keep it simple, most people just go for basic bolt ons. Intake, header, exhaust. IHE. Ill add that for most cars, especially cars under 2.0l and non vtec models dont gain much from those mods. Even then buying the wrong part will net you nothing. To keep it quiet, stick with a somewhat stock exhaust. Anything other than oem is louder i dont care what people say about how quiet it is.
For suspension dont buy cheap shit and make sure u get shocks too. Price doesnt mean something isnt cheap shit.
Research and take it step by step before you buy.