First off, you are right about the 20G. That compressor wheel belongs in the TD06 housing. The ported out TD05 housing doesn't cut it...still too much heat and does not flow well. As for the Big16G - 18G comparison, they are NOT the same turbo like wesman said. The Big16G inducer is about 1/100th of an inch smaller. Both flow around 550 CFM. Only big difference is price. The Big16G to me seems like much more "proven" turbo. There's a bunch of DSMs running mid to low 12s with them. Not bad for a $800 fully ported and clipped turbo. Also, the 16G and big16G use the same compressor housing. One just uses a bigger compressor wheel inside. 2.365" compressor exducer diameter compared to 2.680" on the big16G. Hope that helps.
