Anyone that says put a T4 on a DSM needs to do some learning
What is an option is a t3/t4. Most poeple use the stage 3 wheel, and one of the many TO4E wheels on the cold side, in a TO4B or TO4E housing, and the TSO4 housing on the really big wheels. Examples of T$ compressor wheels are 50 trim, 54,57,60, and 60-1 trims. You may haveheard of these since some poeple just use the compressor wheel name when you ask what turob they have. FOr example, if someone asks me what turbo I have, I dont tell them its a TDO6H turbine wheel/shaft in a 7cm mitsu housing, with a GT30/40 hybrid wheel in a TDO6 cyclone compressor houisng. Its just a GT30/40 hybrid.
The most common upgrades are the 16g and 20g. More nad more people though are getting into garret wheels or whole turbos. For explanations of these sizes and your options, visit turbo vendors like
www.slowboyracing.com,
www.forcedperformance.net, etc. Hope that helps.