Thought you guys might find this interesting when comparing Garrett turbos versus KKK turbo.

For compressors, Garret and KKK use a Trim number. Garrett's trim number is a ratio of the area of the top of the compressor wheel to the bottom of the compressor wheel. For instance: When garret says a 50 trim, they mean the area of the inlet is 50% of the area of the base. take a T04E 50 trim wheel. The base diameter of the wheel is 76.2mm(3"). That makes an area of 7.06 sq. inches. The top area is 50% of that or 3.53 sq. in. working backwards gives up a top inlet diameter of 2.12"

"KKKtrim" is a bit different. They specify compressors by numbers like 2760 or 3060. The first two numbers is the base diameter in decimal inches. So a 27## has a 2.7" base wheel. A 30## is a 3" base wheel. The 2nd pair of numbers is the ratio of the diameters (not the areas). So a 2760 has a base diameter of 2.7" and a top inlet diameter of 1.62" likewise a 2672 (rs2) has a base diameter of 2.6" and a top inlet diameter of 1.872" In Garret speak, the RS2 would be a 51.8 trim compressor wheel with a 66mm base diameter. The RS2 comp has a 2.7" compressor wheel (71.12mm) with a top diameter of 1.872". This is a KKKtrim 2770 wheel. Garret Trim is 48.

What use is all this? Say you want a Garrett wheel that will be similar to a RS2 comp's compressor characteristics. Look for a Garret 12 blade compressor wheel with a base diameter of 71mm and a trim around 50.
The original GT35 has a 71mm wheel and a 50 trim. And lo and behold! the map is very similar to an RS2 in terms of where it falls with regards to PR/and flow. The Knee of the map is even similar in shape to the RS2. You'll find these map similarities exist when comparing a K24 map to a similarly sized Garrett compressor.

For turbine wheels and housings. KKK designates their housings with a stamping on the inside of the inlet. Looking through KKK tech papers this number is the A/R of the housing. So a K27 9.11 housing with a 9 stamped on the inside of the housing is a .9 A/R

Garret A/R is listed in their catalogues.

most updated PDF on K27 turbos and sizes. Better than the K26 and K24 literature at the moment

Garrets PDF catalogue