Is there any aftermarket turbos that could potentially use the 10.5 hotside out of an 05 evo?

yah the 20g , tme, or the stock 9 turbo r the only ones i know of

PhoenixEvo is right, that's about it, nothing else will have a mount for the WG actuator and I don't think you'd want to mess with making one yourself.

With the IX and 20G-9 you may need a different WGA setup than what comes stock on the '05's. Better check to see if the WGA bracket is the same on 8's and 9's.

wga is different on viii and ix turbos

can any other turbos be converted to use the stock hotside? since its a 10.5

No. There is one company that uses the stock manifold, and that's ATP. Other than that, guys like you and me (you'r probaly looking for low spoolup time as well, I'm assuming) are out of luck.

We left a couple off the list:

1) Forced Performance White Rabbit

2) TME-9

3) The uber-expense, ball bearing hybrids, from Essex Turbos & Turbo Dynamics

And sucker ATP

anyone think there is a way to make a 25G turbo mate to the 10.5 hotside?