Jamie
Please don't run this unless you've had all balanced together. If you don't it will almost certainly self destruct very quickly! I'm not trying to put you off but you've gone to a lot of effort to build a great turbo and for the sake of £50 it's not only a necessity but common sense to do, £50 balance compared to a new engine that's eaten your turbo?
You are absolutely correct in thinking the parts are factory balanced but this is only to a set standard to ensure that when they are stack balanced they can be balanced to the required specs. To give you an example I recently got 2 new original BW items balanced. They as a unit where 4 times over the acceptable limit! In other words although individually ok as a unit they weren't. Tolerances for a mated unit is much higher than singular.
If you are using an old turbine there is absolutely no way it will balance up with a new compressor if you just mate the 2!
Honestly I'd hate to read in a month or so time it exploded!
£50 is all it'll cost you for piece of mind.
