I know 3 mopar racers that switched to TH400's and improved et. I don't know if this was due to a better converter or if the TH400 is more efficient? The best improvement in one of those cars was almost 2 tenths, motor and rear was untouched, all mid to low 9 sec cars.
Anyone else had the same result ?

'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03