If you can wade thru the countless posts, there is some good info there. Its a 2.4 Liter but there are enough direct comparisons against the 50 trim and GT3076, etc. etc. to make an educated decision.
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has some direct dyno comparisons of the GT3071 & GT3076 on an Audi. They also have dyno comarisons of the GT2871 and GT28RS I used for baselines. From this I used to deduce the spool differences between them. IMHO both the GT3071 and GT3076 looked fairly laggy on their dyno.
I've been debating myself: BB 50 trim, 20g, GT3071, or GT3076. I'm leaning towards the BB 50 trim myself.