For all that stuffing around fitting a twin scroll turbo off another platform I hardly feel the gains are worth it vs the cost/skill/effort required.
For eg; run a FP 68hta if u want 16g like spool but more power, the wheels more efficient ~20g size and it runs an 8cm not 7cm housing with a Td05 turbine.
(As you say, a 20g is to some extent wasted on a stock 7cm housing with Td05 turbine, with pump fuel, that's why FP now run an 8cm housing.)
Or FP green if u want a tad more. Or bolt up BEP housing hx35.
An example; is a user on here *he may chime in) and a mate of mine swapped the 6cm housing out for a 7cm on his 14b, and the improvements were great. So stuffing massive compressors in restrictive hotsides isnt ideal on pump fuel, race fuel or E85 hides the problem a bit and people can run a lot of timing and boost on restrictive hotsides.
If your going through all the stuffing around of fitting a twin scroll evo turbo you may as well go t3 or t4 twin scroll, but look at the can of worms that opens for cost and fitment.
But now with the power your able to make looking at forged motor build, gearbox upgrades, or at least buying a spare stock block and a good tune, still going to eat gearboxes unless you upgrade them internally.
If your going to open the twin scroll can if worms why restrict yourself to stock frame evo upgrades, which are a compromise for strait bolt up fitment to an evo X.
If you adapting that to the vr4 put your money or fabrication skills into a t3 or t4 open or divided setup, or live with stock flange upgrades and spend the effort optimising the rest of the setup around it.
That extra couple hundred rpm spool your chasing can be found in optimising everything else in your setup around your power goals.
Or you go all out with a build.
If your wanting to run 30psi aussie pump fuel is shit (worse than what the American guys get) , so your looking at E85 or water meth Injection, if your creating that sort of heat.
I wouldn't want to tune the car so its "water/meth dependant". If the injection fails, bang. That's where fail safe systems come into it, or tuning it to the edge that pump fuel will allow, without the water meth and then turning the system on, adding it as a safety buffer, at the loss of some hp.
If you have E85 readily available and you want 30psi, run a good spooling stock frame turbo, run an external wastegate off the stock flange housing O2 housing like punishment racing and MAP make (these are nade in either the gate vented or plumbed back in, all bolt up) to control the boost curve and make more torque and power on E85.
This will yeild a better result than the effort of adapting a twin scroll evo turbo then going oh...... im restricted with the tune by crap aussie pump fuel.
(orrrrr fp green is a killer pump gas turbo, just saying)
