97 540. power potential?

I have a 97 540i, and someone told me that it is the same engine that isin the m5, just tuned down a bunch. I want to know how i can get around 400 hp out of it. Thanks guys.
Chris

I have a 97 540i, and someone told me that it is the same engine that isin the m5, just tuned down a bunch. I want to know how i can get around 400 hp out of it. Thanks guys.
Chris

The 540's engine isn't the same as the M5. The 540's engine is a 4.4 Liter while the M5 has 4.9 Liters. There are multiple options for increasing power, it all depends on how much you want to spend.

Well...obviously the cheaper the better. But I need it to be reliable as well as powerful. And I was definitely hoping to keep it naturally aspirated. One of the guys I have been talking to said I could get an extra 60 or 70 hp out of just putting a new chip in it. Then on top of that, just some simple mods should put me close to 400. I don't know how true this is, he was almost a stranger to me.

What do you suggest to put me at or above 400?