Put an auto in it and see if you can spool that
An auto wouldn't spool the turbo I have anyways, but you send me the 2.6" charger and I'll put an Allison in the truck and spool it...
ANY t6 charger has the same area of hole diameters going into the turbine inlet, no matter how much volume you have in between, so at 3,000 rpm on a stall converter the exhaust gases will be hitting the turbine wheel at the same velocity.
I'm 15.2:1 compression and with my cam, I'm more than confident I could make it spool, I know with the Goerend converter of my choice I could get 3200 rpm with good brakes. Can and heads have FAR more effect on spool than exhaust length or volume, length can hurt you from heat(energy) loss though...