I've got a JDM Evo VII and it was recommended to me as an upgrade, to swap my stock 9.8 T to a IX 10.5 T. I saw an E8 10.5 T for nearly half of the price of the IX turbo. Are there any fundamental differences between the two, and which would be a better upgrade? Thanks!

 

There are some differences, here is a link, evo ix turbo is pretty much better all the way around.

https://www.evolutionm.net/forums/en...low-rates.html

bout halfway down the page. Also... | 8 turbo is on the right.
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Is your VII turbo in good condition? If so, you could just swap your 9.8 turbine housing for a 10.5 housing. This would give you essentially the same thing as an Evo VIII turbo with a 10.5 housing.

I think that the VII and VIII turbos are identical. You can just swap turbine housings. The VII and VIII turbos have the same compressor housing, compressor wheel, and the same turbine wheel and the turbine housings are interchangeable.

The IX turbo has an improved compressor housing compared to the VII and VIII turbos. But, other than the comp housing all three turbos(IX, VIII, VII) share the same rotating assembly and they all can be configured with any of three turbine housings(9.0cm, 9.8cm, or 10.5cm).

The IX turbo due to the improved comp housing is worth some horsepower over the VIII and VII turbos. For some reason though the IX turbo is a bit more prone to boost taper than the other two turbos.

Take the IX turbo over either of the other two.

 

The ix has a larger cover due to the compressor wheel being different. It has a larger diffuser

 

You are partially correct, awdordie. The diffuser is formed by the back cover on the compressor side and part of the volute housing. The diffuser on the IX turbo is indeed different than the diffuser on the VIII turbo, but the difference in diffuser is due to the difference between the IX vs. the VIII comp covers and the way that they mate up to the center housing. The compressor wheel itself however, is in fact the same and unchanged between the IX and VIII turbos.