2006 325i had the same 3.0 six [N52], it was detuned version of 330i engine, 2007 328i is a similar engine [N53]
2006 BMW 325i Featues & Options - Automobile Magazine
"Slightly confusingly, both the new 325i and the 330i have the same 3.0-liter inline-six. The 325i has retuned software and a different exhaust and intake system, lowering power and torque from 255 hp and 220 lb-ft to 215 and 185: the 325i would need only ten more horses to fill the previous 330i's stable."
If you use DINAN you should be fine regarding upgrades (
Dinan BMW | BMW Performance), my dealer sold me dinan ecu for my 540i and warranty was kept intact. IMO it's best to get the 2006 325 or 2007 328 and mod it a little to make it a 2006 330i, of course if you resell it soon you won't get this value back, but if you plan to keep it for a while it's worth it.
EDIT: I found dinan doesn't have software for e90, but see the following article to make a 325/328 into a 330i on steroids:
2006 BMW 325i - European Import Tuning Guide - Eurotuner Magazine
Quote:
Originally Posted by Exacc
325i engine has 2.5 liter displacement, while the 328i has 3.0L displacement...
Flashing the car will surely void BMW warranty.
In the E46 era, the 325i was the upgrade of the 323i, while the 330i was the upgrade of the 328i.
Now I am confused, because I think they sort of downgraded...330i to 328i and 325i to 323i....and on both cars, the engine output also lessened. Weird  |