[JSeery]

I would bet the return holes are there, they can be hard to see. There is really no reason they would not be there unless it has been modified for some reason, which would be odd. The restrictor on the inlet side can likewise be somewhat difficult to locate. It could in at the fitting coming out of the block or inside a T-type fitting going into the canister. It can probably be in other locations.

If you find you do need to add a restrictor they are available, they are also used on turbo-chargers.