Hi all,
My car is currently in with a workshop to have the dyno tune completed. I am unsure about how much boost I should ask the tuner to use. Obviously o2 readings and knock will be a limit at some point. It will be running on pump gas (equivilant to 93/94 in the USA). I would appreciate advice from members on here with direct experience.

Engine setup is:
9.0:1 forged pistons
Aftermarket rods
ARP head studs
Cometic head gasket
ID1000 injectors
300lph fuel pump
Fuelab fuel filter and adjustable fuel pressure regulator
Forced Performance GT35R with 0.68 exhaust housing
Larger intercooler w/ 2.5" intercooler piping & Tial BOV
Degree'd Kelford 272 cams with dual valve springs
3" Exhaust
Standalong ECU

Cheers!
Ryan

.68 turbine housing ....

If you had the larger housing on there and you had a competent tuner 30-35 psi making north of 500whp would be pretty easy to hit. I wish they never made housings that small. I did a test on a galant, went from a .55ar bolt on housing to a 1.0AR T4 TS housing and picked up 80whp at the same boost level and it spooled faster(Same turbo)

Oh well, its on there now and Im sticking with it. Will be a big change from the 16G anyway. Car has started to have the tune down today. Will know power figure tomorrow.

To be fair twin scroll will spool faster, the t4 housing is probably tangential instead of on center and I'm not 100% sure but I don't think you can compare the area to radius ratio of an open housing to a divided. Plus you need a t/s manifold, possibly to external gates, but they are by far superior and well worth the extra money imo. Although now that I say that I think fp made the turbine housing tangential and that's half the reason the flow so well.