Turbo need hot exhaust to spool up. It takes around 10min for the N54 to warm up to the ideal operating temp. Most test drives don't even last long enough for the engine to warm up.
The 335i is a huge leap from your 328i. The amazing torque curve should leave you feeling satisfied. If it's not enough power out of the box, you can bump the power up with a simple tune. Much easier to get power than an N/A car.
