yeah i'd definitely go with a 2-1\2in zorst system with a resonator and straight through muffler.
Power wise, if your getting 200HP at the wheels, that will be one mean hybrid engine hehe. You'll have to take me for a ride one day. On the street, you'll love it, and on the track you'll be smiling from ear to ear. I'm looking for an excuse to go to mallala again so if you're going out there, give me a heads up.
I'm making about 150hp at the flywheel (it dyno'd at 80rwkw at 6500RPM, but i had to rev limit it to 7400ish) and that is with a stock 2TG engine internals, but with modified inlet and zorst system (i was lucky that i had a 4-1 zorst that collected together at 2-1\2in). If i was you, i'd get a set of headers made and that way they can custom make it to suit your porting too. Plenty of shops used to do this around Adelaide. I'm happy with mine at the moment considering its a stocker on the inside. It pulls hard enough for an old car. Once i build a hybrid engine though, i'd like to see what you guys are getting, 200-250, but i may later change my mind as a 250HP T series engine is no-longer really street-able.
keep us posted