I went to the dyno with the ol' z. I made 322.2 rwhp and 332.3 rwtq. only mods, lid, pulley, borla C/B. Not that its that high i just think its kewl when its got 108,000 miles on it and i drive it to work everyday 75 miles.
My 98 WS6 w/ 73,000 only put dow 315/329 with Lid, Hooker cat back, MAF, K&N, Random cats, and free mods. The afr was 11.5:1 though. I would say you have great numbers. I guess the UD pulley is helping. I have to get one of those. Congrats.