Why don't you look for a used turbo or a complete engine - used turbo would cost you couple of hundreds euro/pounds and the complete good M57 engine form a car with service book costs like 1000 Euro. Engine Installation would cost 500 Euro + lubricants.
By the way - if you own a 930 Turbo you shouldn't have any fears about fixing costs of X5 - they're just a baby toys, compared to the maintenance of an old 911 turbo.
|