hmmm, so in the entire intake and exhaust system, top end, cams, compression ratio, squish band, all that stuff and whatever else is involved, there are no improvements to be made? no gains to be had? no emmissions issues or compromises to be got round?
Wow, thats got to be a first for production engine.
218 odd bhp from a 3.2 for example? not bad i guess, but surely there's more in there somewhere?
There's always more to come from an engine, it's just a matter of paying for it.
There isn't a lot to be gained by chipping one (OP's question) IMHO and, given the cost involved on these ECUs I would doubt it's worthwhile.
Now, if you were to strip the engine and start again you could probably get quite a bit more power out of it by addressing the areas you mention and others but these days standard production engines don't generally have weaknesses that can be
easily exploited for more power - naturally aspirated engines, at any rate.
Kevin