how much horsepower can the 904 take?

904-spring.jpg
TF904 Reverse Wound Direct Drum Spring

Description
Part #
Price

904 REVERSE WOUND DIRECT DRUM SPRING
904208
$19.95
One of the things that you need. The Factory spring unwinds itself at high RPM. This replacement is wound the opposite direction so that doesn't happen. Much lower price than that multiple spring kit from a & a.

ATI Racing Transmissions - Chrysler Torqueflite TF904 Drag Race Transmissions