Could you not have got the same "feeling" from fresh RP fluid?
When I took out my factory fluid at 60K miles, it was basically done, shifts into 2nd were difficult, fluid was dark and had sediment (no track time.) I don't consider the RP I put in to be a long life oil, and will change it at 30-40K miles, and I'm very satisfied with it's performance. I put RL into the diff, that I'll keep in longer, probably 60K (if I still have this car.)
UPDATE: I changed out the RP Sychromax with less than 1 yr and 10,000 miles. Was brilliant for a just a few months and thousands of miles, then became worse than my old factory fluid over several months.
I went with RedLine ATF, as I had it in my E46 and it's improvements over the factory oil lasted. When I spoke with RL tech support about which RL to use, he said the viscosity of Synchromax is heavier than the RLs or factory. I know that color doesn't mean a lot, but bear in mind that it was a light purple color going in, and less than 10,000 mls.
UPDATE 2: I saw later on RPs website that Synchromax is compatible with MTF-LT-1, but not MTF-LT-2 & 3, which is what E90 transmissions use -- it's too viscous. I should have checked that before
using it, my bad.
I like the way the Redline shifts, warms up quickly in the middle of winter, shifts are effortless, but direct, and quick. Their tech support was very knowledgeable, helped ID a clutch problem I was having: