Originally Posted by simianspeedster
I know you're mostly referring to the numbers and not the experience, but a heavily overboosted, relatively small displacement 4 will never feel or perform like a mildly boosted inline 6 across the rev range. It will likely have significantly more lag, be more "peaky" in its power curve, deliver more NVH (of course) and I would be concerned about reliability/longevity if none of the other components are modified to account for the additional power.
No question a chipped 2.0T will be a cheap performance bargain, but a 2.0T +$500 bucks will definitely not equate to a stock 335i.
I would bet there isn't a whole lot of room on the table for performance with this engine. The gains would probably come from reducing back-pressure, improved intercooling, and possibly a less restrictive intake and a tune to accomidate these improvements. I'm 90% sure you wouldnt see the same percentage level of improvement as the N54 per mod.