Okay, so you want your ride to go faster, and sound meaner, so what do you do? Mild Jobs: Cold air intake Free flow header Cat back exhaust system(for that gorgeous sound) Fuel pressure regulator(Rising rate) making sure your engine isn't starved of fuel at wide open throttle. all of this should you cost you in the region of about 35k, with top notch branded stuff. This is what i would recommend to a person who is constricted by his finances or who has got a car with an engine capacity less than 1300cc. This should/will give you an increase about 10%. And on a small car its going to be even more noticeable. Exhaust systems and intakes are designed to manufacture specifications why are driven by financial concerns as well as packaging constraints. So by doing some of the previously mentioned mods, you are basically helping the engine breath freely and allowing some of the horses that were there, find their way onto the tarmac. If you don't feel satisfied you can also go for retune of your ecu, but be warned, these are not cheap, and you can't return your car to stock either, however, you can also go in for a piggyback unit, which won't be as effective, is cheaper and is quite less invasive, also you'll be able to return the car to stock mode when you do finally sell it. ECU remaps, allow you to get the maximum out of your existing setup with a tailor made fuel and ignition maps to suit your driving style. Something a piggyback ecu can't do. However, some ecu's can't be remapped so please research on the net before assessing the suitability for a remap.