Ok I guess let me give you this word of advice. I myself am one day going to shot for 500. Right now I'm at a very reliable daily drivable 327 HP 301 TQ. The only reason I don't daily drive is my work provides me with a company vehicle.
When you hit around that 500 mark in a rotary their are certain things that should be done internally to the motor to ensure your going to last under continuous applications of stress.
List of thing I plan on adding / changing in order for myself to hit 500
Large Streetport
3mm seals
Motor doweled <--------------- 100% should be done at that HP level
HKS T04Z
1300 secondaries
850 primaries
dual supra pumps
50/50 water/meth injection
vmount setup
My current setup
-Stock motor 74k Original miles
-Stock twins running non-sequential via PFC
-Greddy pulleys
-Pineapple Racing idler pulley
-K&N filters
-APEXi AVCR
-APEXi PowerFC /w commander
-full turbo back exhaust to RE Amemiya T/A dolphin tail muffler
-Supra TT fuel pump (relay wired)
-Efini Y-Pipe
-Trust SMIC
-Greddy Elbow
-J-SPEC 5 speed transmission
http://i21.photobucket.com/albums/b2.../FD/myrun1.jpg
Hope that makes sense in what I was trying to ask you.