Jonny, before super charging etc you really need to know if your crank and bearings will take the hike in power. I don't know much about the internals of your engine but am sure its been fitted to other models in the bmw line up? Try finding someone who has already gone down the tuning route on other forums and learn from their progress/mistakes. It can save you loads of money and heartache.
I will be amazed if you get anywhere near 20hp from a remap, to be honest I will be surprised if you actually gain any HP. You will get a more responsive set up with a nicer throttle. . But any extra HP is doubtful. They work well on turbo charged engines but not so great on N/A buddy.
I will be amazed if you get anywhere near 20hp from a remap, to be honest I will be surprised if you actually gain any HP. You will get a more responsive set up with a nicer throttle. . But any extra HP is doubtful. They work well on turbo charged engines but not so great on N/A buddy.