Does anybody know the significance of the different colored backplates on Turbonetics turbos? My friend bought what was supposed to be a DBB 76mm and to me at least it doesn't feel like it spins any more freely than my journal-driven 67mm. It has a gold backplate on the intake side and I remember reading something once about the difference between the gold, blue, etc. but I can't find it again.

He tried to call Turbonetics and couldn't get ahold of anybody so I thought I'd ask here.

 

the main difference with DBB is that it requires water cooling? lol

 

I know, but the backplates have something to do with what series the turbo is.