What dyno was it?
On a Dyno logic one, I've seen an R34 GTX-T series 2 get 169rwkw running about 12psi, stock ECU and CES 3" Exhaust (split dumps), auto. A series one auto R34 GT-T with nothing but K&N panel filter, stock boost and an Apexi Cat-back 3" exhaust do 147rwkw. Neither car had front mounts.
Mine has more than just exhaust and boost so I won't post mine.