Do you mean the "Secret Sounds" ?
Mostly those are nonsense, combination of suggestion and folks listening with their eyes.
One need only spot the inclusion of Stingray settings as evidence. Stingray has a fairly hot humbucker, tamed by parallel wiring, placed in a specific "sweet" spot and paired with active EQ; T-40 meets none of those conditions, certainly not with the suggestion of just using the bridge pickup and placing it in single coil mode
It's rather poor at EB-3 or 70's Telecaster bass despite having a humbucker up by the neck. Gibson stuck a 30k ohm humbucker up there, Fender's WRHB was in the high 20's; the T-40 humbucker is about 6.7k ohm. Pickup positions are well out from coping a P-bass tone, even if you physically rotate the pickups. Then there's the fact, in no universe does a 51 single coil P-bass sound the same as a split coil P-bass.
It does manage a jazz bass style tone, which in turn means it can cop a Ric style tone (in the right circumstances). That's pretty much it.
Might appear I'm being overtly critical regards Peavey. I'm not, I'm critical of the myths