Quote from Grahameo
"Welcome to Q-system ownership.
They do take some getting used to in order to get the best out of them... But... They are really bullet proof and the Aisin 4 speed box is tried and tested unit in Lexus and Toyota too.
It's more than capable of handling 400+bhp from twin turbos and big torquey V8's.
A lot of people don't like the tall gearing but believe me, it pays dividends on the overtaking ability at relevant speeds that is somewhat better than the manual 6speed (we have both in our family so I can testament to that) ;-) 80+mph in second isn't natural according to my father in law!
Take no notice of the "official" performance figures either, they didn't even try it in semi-auto H mode when it was tested so it isn't 8.5 secs but 7.4 secs to 60, not many know that bit of useless info.
Sluggish low down of the mark is normal for a new owner, you have to adjust your driving style to prevent the gearbox bogging down... Try half throttle on take off and then graduate the pedal to full throttle as the revs pick up, it avoids all the torque being wasted in one big lump by the torque converter.
Disconnecting and reconnecting the battery and letting both ECU's relearn your driving style helps a lot too
Look under "miracle cure" for details on how too
The ECU is cleverer than the engine ECU too
The only thing you have to do differently with a Q-system is check the ATF regularly while the engine is running (dry sump box) and change the ATF every two years regardless of how little mileage, after that they will last 100,000's of miles without any grief