Rb20 Silver Top Fuel Rail Has A ? At The Back That Looks Like An Fpr

[GTsauRus]

So is it a dampener or is it an fpr?

searching found it called both

It has a vacuum line just like the fpr except that the vacuum line connects to the turbo side of the throttle body.

[GTSBoy]

Pressure dampener. The giveaway that it isn't a regulator, is that it can't regulate fuel pressure, because it doesn't have a fuel line leading away from it.....like a regulator would.

[GTsauRus]

Ok that explaines why its reference pressure line is connected to the turbo side of the throttle body so it sees very little vacuum and higher boost than the manifold does. Thanks for the answer.