how to improve gu auto gearbox

i had a slight sudder going into o/d
changed oil now ok
does this line pressure mod work on 06 3lt
will it effect o/d shifting in & out on h?way {very annoying }
cheers

The "O/D shifting in and out" is probably your torque convertor locking/unlocking which is not only annoying but is also generating unnecessary heat in the trans.
This is why people fit a manual torque convertor lockup system.. as mentioned earlier in this thread.

I'm not an expert on this, but recently have been playing with my auto, and yes this can be one of the reasons people fit the manual TCC lockup. I have one and I use it alot for this same reason, but if I am driving normally at 100kph or above on open roads, then I don't really have the problem. It is normally at slightly lower speeds and undulating highways.

Basically, your TCU has a heap of settings and parameters that dictate when the TCC engages and disengages. Throttle Position, revs, speed etc. It sounds like that position is close to the conditions you are driving at on the highway.

The manual Torque Converter Clutch lockup kit will override these conditions until it is either manually unlocked, or accelerate hard etc.

I've never heard of a manual lockup that cuts out when you accelerate hard FNQGU. Is yours a known brand, or custom built?

Pretty sure it does, although I appologise if I am wrong. Might be a setting on the Compushift II that does it. I will have to try it again. There are so many settings to play with on it that it gets confusing.