What kind of benefits would chip tuning do for my 2000 BMW 540ia?

It all depends. What other modifications do you have and/or are planning?

ive seen, some chips especially on newer cars giving up to 40hp/tq without any other mods, u might need a new ECU to make it worth while, maybe out of an M5?

On non turbo cars there isn't much gain when it comes to power. I would not touch it to be honest, enjoy the 6 cylinder as it should be.

If you have a cold air intake, upgraded coils, exhaust, or even a supercharger, you could remap after each mod. There is even a tranny chip mod for those of you with a slushbox.

Not the kind of work you would do on a BMW 5-series. For that kind of money I would sale the car and get an M5, they are cheap now.

I could not disagree more. While the M5's are less expensive, M parts are still well beyond standard fair. However, I forgot that you have a single Vanos engine rather than the dual Vanos. I could recommend a couple of shops. depending on where you reside.

+1x2 Michael. Price M62 vs. S62 crate motors. Illustrates that point perfectly. Best upgrade for the M62 is the vortech supercharger kit, for like $6000... and then some more on limited slip, you will effortlessly walk an m5. Still seems a little cost prohibitive. AEM make a nice cold air intake (someone used a $2.99 office trash can and a heat gun), cat back exhaust exhaust (stock piping to the cat flows well enough to leave alone already), and mod to fit an intake manifold from the earlier 97/98 540 engines (like the ones dinan rebrands as their own). Then chip it. At that point you might reach the numbers CJ is talking about for a few $1000... at least your auto would be able to rival the stock 6 speed at that pont. :-P