PS. Thanks for the kind words.

All excellent points John. Evidently, you have been doing your home work. I add a few of mine :
On 2 - I'll let you know in a few weeks if this is a DIY bolt-on deal or not.

10. Longevity - with a low pressure system, not trying to exceed the design limits of the engine, I don't think a turbo will have a radical detrimental effect on engine or transmission life. Driving style and maintenance are more important factors.

12. If you have a 325i AT (Don't you have an AT too, John?) a turbo might be cheaper than an M3 motor. I don't know if you can (or want) to bolt an M3 motor to a 325 AT tranny. If you go from 325 AT to M3 5 speed you are probably looking at $4000 motor, $1500 tranny $500 diff and $500 misc stuff = $6500. Low pressure turbo $3900.

13. I don't know if a turbo will blow the doors off of an M3. If you have a 325 with AA stage 1 turbo, probably yes. With a less aggressive turbo system, it'd probably be about even. With an 325i AT Turbo vs. stock M3 5 speed, forget it. I'm expecting 6.5 sec 0-60 with 325i AT turbo. Stock = 7.8?? M3 5 speed = 5.5 sec.

14. Buying a used engine from a high HP car is risky business. You know what you got now, you don't know what you are going to get. The ONLY reason I can imagine anybody selling a M3 motor is because the car was totalled. What if it was totalled from the front?

15. No warranty on used M3 engine. Turbo - 6 months warranty.

Your best point might well be #3. Of course you could rip the M3 motor out again too and sell it, bolt the old 325 back in and recover some of your cost, I do concur with you that you'll probably depreciate more on a M3 motor.

Hey John, on a side note, keep the wife and house buddy. I too have wondered why some of these "young kids" on this board seem to have unlimited funds for toys. I'm in the same boat you're in. Make the same kind of money, got the house, got the kids, got the wife and I don't have unlimited money to spend on my baby. But the reality is : we're doing alright. We have a house, good job, wife and a BMW. Unhappiness comes from comparing...

I enjoy your posts.