Looking for anyone that has run an hta green with the stock O2 housing. Or even another variant of a stock frame turbo. How much power do you think would be held back?

 

Or has anyone just swapped the compressor side of the turbo while the hot side was still attached to the manifold and motor?

 

The turbine wheel is to big to swap like the HTA71. The housing has been machined for the larger wheel. Based on a couple of things I've read, I would guess you'd be losing almost 15hp sticking with the stock O2 housing.

https://secure.buschurracing.com/catalog/product_info.php?products_id=714

 

Ok perfect. Wasn't sure if I could just swap the compressor side and not have to remove the hot side from the car.

 

You can use the stock O2 housing. The turbine housing will need to be machined out for the green.