there's good and bad to both if I was hauling heavy all the time and didnt plan to tune yeah I'd go aisin but keep in mind price tag of aisin plus 3500 no trans tuning available and doesn't like any added power for those reasons I went 2500
If you donít like how the truck runs, your pretty much stuck because the Aisin canít be tuned. I live at high altitude and the dead pedal and slowness drives me nuts but there is not much I can seem to do about it. Tried with a emissions in tact tune from calibrated power and it only made more top end power and nothing to improve response and low end. In fact it towed worse in the lower rpm range so I removed it and now have an expensive paperweight.
Drove a 19 Aisin and although the 3.73ís help, I am not convinced that it is enough of an improvement for me.