Joe on the forum has suggested these guys
The bloke that I use does a brilliant job. Rowville Exhaust, Fact 1/ 12 Hitec Place in Rowville. Ph: 9764 1177. This guy is really good, he's done all the work on both of my cars and never done me wrong. just explain to him what you're trying to acheive and he works out the system for you.
There isn't a blow off valve on those cars so you don't need to worry about that.
Make sure the exhaust has a 3" dump and mandrel bends all the way through. A hi flow muffler will make no difference to the results of it is personal preference.
We had ours done it cost us $850 for everything about 12 months ago so that should give you something to work to.
Once completed put the thing on a dyno and have it tuned then you will notice ther differemce. We picked up an extra 30% having the exhaust and tune done.
These guys are meant to be pretty good with Patrols
Mannell Motors .::. Everything 4WD might be worth chatting to them.
Hope this helps,
Cheers