Those of us that read here would know there are some pretty crapy GT30 turbo's available from Garrett.
As mentioned before the "real" GT30's run a chra part number 700177-6 or 700177-7. Both of these run the GT30 series 84trim 55/60mm turbine wheel however they run different trim compressor wheels.
The -6 runs a 52trim wheel and the -7 runs a 56trim, both I believe are 6 blade wheels in true GT design (high speed and much more efficient).

Is this 56 trim wheel as fitted to the -7 chra the same comp wheel as fitted to the 446179-32 chra?
When comparing the real GT30's (above) to the T04S GT30's do they have any downfalls such as having a lower hp capacity due to the lesser comp flow or does the overall efficiency make this not an issue.
Looking to run approx 400-450WHP with genuine 0.82a/r turbine housing.

It seems above these spec GT30 turbos the next step is to go with a GT3540 chra706451-5, but this is a big step and I question how good this would be in a street/social drag application (for my personal liking anyway).

-32 ? Have to look that one up . 446179 sounds like GT28 turbine based .

Found it , -32 is a 56 compressor trim GT2871R so no that wheel is a 71.1mm 56 trim GT35 series compressor , the 76.2mm GT37 series compressors are used in the "real" or ball bearing GT3576R/GT3037 turbos .

The reason GT compressors work better size for size than the older compressors is because they have a different blade form and compared to a TO4S wheel less blades . If you sat them side by side the angle of the blades is sort of more towards being diagonal than vertical and the exducer tips are layed over rather than being almost vertical and a bit more swept back as well . Its all about having less innitial "bite" into the atmosphere so that the GT turbine can zip it up to speed to get the show on the road .

The unenlightened like to think that big compressors that can churn a lot of air at low (for a rotary compressor) revs have to be good . The realiity is that the big wheel won't move a crows fart if the turbine hasn't got the exhaust energy to drive it against heavy compressor work loads at low engine revs and exhaust velocity .

Look at it like this , your car would be a slug off the line if you had to start off in 2nd or third gear all the time because your engine like the turbos turbine won't produce much torque at low revs . If you could reduce the mass of your car by 1/4 to 1/3 getting started in the higher gear would be less of an issue because the engine has less weight to shift . Same with the turbos turbine if the work load is less at the spool (boost threshold) phase .

Cheers .

I require a little more info between the two gt3076 turbo's below.The-
700177-6 which has 52 trim comp wheel &
700177-7 which has 56 trim wheel.
I am trying to decide which of these I should be getting. I would expect the 52 trim would have superior spool/response but it would run out of air before the 56 trim.
Hopefully discopotato can step in here and give some guidelines in terms of power that would differentiate the two apart a bit more.

It seems at this stage the progression of power in turbo's is-

gt2860 true "disco potato" turbo
gt2871 larger comp wheel chra-446179-32?
gt3071 gt30 turbine with 56 trim gt35 comp chra ??
gt3076 gt30 turbine with 48 trim comp chra ??
gt3076 gt30 turbine with 52 trim comp chra 700177-6
gt3076 gt30 turbine with 56 trim comp chra 700177-7
gt3540 true gt35 chra 706451-5

I have listed only what is considered to be good matched combinations for performance applications.
If this list is not correct please fix it.

From what I've seen the map I believe is the one for the GT3076R/GT3037S 52 trim shows ~ 49 lbs of air at approx 2.4 pressure ratio or about 20.5 lbs boost . This equates to 709 CFM at 60% efficiency . These are maximums .

The map from the 56 trim GT3076R shows ~ 53 lbs air at about 2.75 pressure ratio or 26 lbs boost and 60% efficiency . Again these are maximums .

Personally I always look at what the map states along the 2 pressure ratio or 1 bar (14.7 psi) line . The 52T map shows a little higher max efficiency (78 vs 77%) BUT it spans 23-37 lbs air range where the 56T spans 27-36 . At 74% they show 20 - 42 lbs (52T) and 22 - 42 lbs (56T) .

In very crude terms it would appear that the 52T version is a whole 4 lbs down on maximum airflow (equal to about 40-44 Hp) but only if you ran it to the bleeding edge and have an engine of very high volumetric efficiency which production engines don't . To quote someone in the US who worked for Garrett 400-425 Hp 52T with .73 A/R turbine housing , 475 Hp with a bit more lag 56T with .87 A/R turbine housing .

In basic terms this means if you had a race engine and the top end was a little lacking go the 56T , for anything less than a drive it at maximum revs and boost EVERYWHERE use the 52 trim . My advise is to err on the conservative side here because if the first 90% of the usable rev range works for you thats good . If however the last 90% works well you ALWAYS have to get through that dead part first and its generally right at the point where you drive the thing much of the time . Far easier to live with good 90% of the time than 10% of the time .

That list you typed out is about right for Garrett marketed turbos though I would have said the 48T GT2871R or cartridge (CHRA) 446179-5031 .
If you were prepared to spend HKS dollars you could splice their GT2835 series turbos in 48/52T (remember cropped GT30 turbine ONLY any good in HKS GT30 based turbine housings) in between line 3-4 ie between 2871 and 3071 .
In between line 6-7 you could slot HKS's GT3240R wich is a cropped GT35 turbine with a 54T GT40 compressor so a little more responsive than a GT3582R (GT3540R) . The Evo crowd claim about 540 odd Hp from them with highly developed engines , the sticking point is that they are only available with 1 turbine housing ie .87 A/R T28 flange non gated .

Your call , my vote to 52T GT3076R/GT3037S .

In regards to your last comment of you choice being the 52T GT3076R/GT3037S, would you recommend the .63 or the .82 A/R turbine housing..? What would be the difference between the two in terms of response and overall power..? I'm aiming for between 350-400 rwhp.

Cheers.

You would have to base that decision on where you want the power to be . Those turbos have port shrouded compressor covers so surge should not be an issue . There is a third option which is the .68 A/R HKS GT Pro T3 flanged integral gate turbine housing but possibly hard to find . If you can't make up your mind go conservative (.63) and if possible get it extrude honed just to smooth it up internally . If you did not like its result the housing would not be difficult to sell and recover most of your nmoney .