I'll just say for the turbo replacement on my 335i out of warranty was about $6000. I also had constant misfires and had to replace the coilpacks,
spark plugs, vanos solenoids and that bill was about $1000. After the turbo replacement I would get an overboost issue any time I was in boost for prolonged periods. That was all to repair the car, not modify it. Worst car I ever owned and since it was never mechanically sound I couldn't use all that "power."
I would say if you don't mind that when you run into a problem the endless hours of troubleshooting and also the incredible amount of money to fix it then get a turbo car. If BMWs are the standard of engineering like the whole automotive community seems to think then I would recommend staying away from FI cars. If you do happen to get one keep it stock because the minute you modify there goes your warranty and any ounce of reliability the car had to begin with. There is a reason the 335i is considered one of the least reliable cars you can buy used. And for the money you pay new they are severely overprice as the interiors are just rubbish. The fact I can get a Genesis for $23,000 with an additional 85,000 mile warranty says a lot for what you can get these day. Having a BMW is like dating a model. They are sure pretty to look at that's about it.