Anyone running a 904 behind a 340?

Agreed !! My 904 has the ati 30 element sprag, an aluminum front drum and a billet brake that leaves the band on till 2nd gear, solid a&a low reverse servo kit to speed release and John Copes recommendation for a double wrap low band adjustment of 1-1/2 turns versus the factory 4 turns to speed the release of the band.
Yes, lot's of little things make them work more efficiently.
It can be hard to make VB's work exactly the same way on transmissions when they have all different types of bands, clutches, clearances and spring loads. That's why a Manual VB install usually requires a transmission overhaul as well to get the most out of it.
Glad we sorted out the confusion.