Walnut Blasting

Just after a bit of advice on walnut blasting.



How do you know if it's needed? Just about to hit 60k on my 2007 335i.

Rough idea of cost?

Any decent places near Manchester/NW? (I know a decent Indy, not sure if they have the equipment)

Anyone that's had it done noticed a difference? (Performance, economy, running smoother?)

And would you get an OCC after getting it done it does it not make a difference?



Thanks