03 330i

Start with a higher flowing airfilter, just a panel replacement as a pod filter have to be blocked off from the rest off the engine bay to get good gains as you need cold air to make power(more oxygen in cold air) and a larger diameter exhaust system(mandrel bent), this will free up the flow on both ends in and out. This is aways the first performance modifications to do for any standard car and the best bang for buck. Remember maintainance is the best foundation for performance, remember maintain before modify ie good plugs, fuel filter, clean airflow meter,leads, timing, oil etc... and will also be more economical on gas and make it last longer.I hope this helps.If you want anymore info on peformance just ask.