Does a jury need to be instructed that hearsay statements are admissible under the coconspirator exception?

"[O]nce the judge determines that the hearsay statements are admissible under the coconspirator exception, the jury should not be instructed that it must determine admissibility." United States v. Peralta, 941 F.2d 1003, 1008 (9th Cir.1991), cert. denied, --- U.S. ----, 112 S.Ct. 1484, 117 L.Ed.2d 626 (1992). However, such an instruction constitutes reversible error only if a defendant demonstrates that the instruction was prejudicial. Id.; United States v. Lutz, 621 F.2d 940, 946 n. 2 (9th Cir.), cert. denied sub nom. White v. United States, 449 U.S. 859, 101 S.Ct. 160, 66 L.Ed.2d 75 (1980).