hello , the question is As above and what difference does it make for 60 a/r or 64 a/r ?

There's no .60 or .64 choice for the GT28RS. You can get either .64 or .86 AR hot side (turbine). Cold side (compressor) is always .60 for GT28RS unless you get some sort of a hybrid. Talking about hybrids you can chat to Flea (FC Performance) as he has got a wide range on offer. Also a great hybrid is GT28RSR which you get get from CR Turbos for example. It will cost more than GT28RS thou.

Bigger AR on the hot side will make the turbine flow more air and give more top end performance but will result in much later spool.

I have replaced my GT28RSR .64 with GT28RS .86 and I much preferred the RSR for street use. Also my OEM injectors will be maxed out. That said, I am still waiting from Flea to correct my map taking into account the new turbo.

My advice would be go either for GT28RS .64 or GT28RSR .64

Oh, kj16v will be testing Kinugawa turbo on his 20VT project. Speak to him to find out if he's made any progress. Coule be cheaper alternative with good result?

Also, don't forget about supporting mods, FMIC, FPR, EBC, colder plugs, remap, air induction, exhaust/downpipe, brakes, suspension and ideally bigger injectors thou you can get away with OEM

I'm also looking for one of the kinugawa's.
Especially the TD06SL02 with either the 60-1 or the 25G compressor.only problem i see is the small A/R (0.57)for my 2.4 i m building.
It seems like the Jap.car- enthusiasts are really pleased with them.

Its kinda diferent world when it comes other brand than garrett all those numbers has different meanings:-D. thanks for answers deannn_20VT. thinking to get a rs one for now with all the mods. probably will stay with original injectors till get my suspension sorted. then hopefully standalone ecu and go forged ;-)