Im not sure (cause I have not noticed any difference), but how is a Turbo high maintenance cost-wise? If you do normal maintenance and dont do silly things like drive hard, then shut down the engine right away, how is it higher maintenance?
Also, we all have our wants... but why would you want 400 hp out of a car like that without a turbo? Seems to me, your doing something to get more power, but dont want to pay the price. Pretty sure if you do all required to push an auto above 300 HP, in the end, your shortening that engine life and increasing maintenance costs in comparison to just dropping in a properly built turbo engine. I have trouble driving sanely with 250 HP... 400 HP... makes me wonder why people want that..
This is, of course, just my comment... but at 400-450 HP.. wouldn't you be looking at offroad racing? (racetrack) The car's damn fast as is.. lol