[M&M]

What's the thoughts on taking out the 9G compressor wheel, machining a 13G in there (I don't think the 15G will fit without changing the whole housing), but leaving the stock turbine wheel in there. Should make a moderate 10-15%power increase on the same boost but hold the boost a bit longer & shift the powerband a bit up. Should be very cheap to do as well.

If you want a bit more, maybe changing the housing to the slightly bigger Td04-H housing with the 13G or 15G wheel. That might necessitate a few more changes though (maybe turbine wheel, etc). The simple compressor wheel swap seems like a risk-free way to gain power with very little impact on spool. Is there something I'm missing here?