guys, i saw that it's a very old problem with lag.
so, may be my hint will help you.
try to add 1 liter of dct oil higher, than normal level.
why?
read below
i had a problem on our tracktool when we swapped dct first time to our n54.
in first test runs i've found that when i'm trying to accelerate immediately after braking (even in street driving), car can lagging for a second or two.
and small retreat - i usually drives on two-pedals cars with two legs, so i have no delay between pressing.
another retreat - our car has 6 pot large brembos on front, with 275/275 semislick setup
.
so, when i saw this lag, i've start to make it again and again easily (yep, this is all about 50kmh speeds on a city streets and braking till 10kmh).
and in after some hard braking i've even make warning on dash and car went to limp mode. than i've switch it off and start again, and drove like it has no problem..
and than again and again, and... it looks like starvation, when your petrol gone away from the pump.
so, i've made a test to check this assumption (i've reading forum and saw that people had this problem on low speeds, but!) i've accelerated to high speed (150-180kmh) and make hard braking on 3 or 4 gear and than quickly made a full throttle. and of course car lagging for a moment and gone limp mode.
after arriving home i've reading fault codes and i saw that gearbox had tried to make a clutch engagment, requested 10 (or so) bar of pressure but get only, 2,4, 1.5 etc bars, but no pressure which it requested.
it's simple - oil under braking goes away from suction pipe and gearbox can't build pressure.
so, when i was doing dct adaptation, i saw some interesting info in ista, that m3 gts transmission has one liter of oil more, than usual dct.
of course, i've checking dct pan in next few seconds in bmw cat
they were fully the same.
after that i looked how m3 gts filling up dct oil and they simply add this liter over the standart level (they use banjo fitting for easily filling this liter).
so i've lifted the car on the right side as high as possible (professional jack) and add same liter of dct oil.
after this i've tested car on the streets as hard as possible (yep, "street driving" up to 250kmh), and problem almost gone -only few times on braking in the top of the hill on 200kmh
i've got same fault.
on the next track day we've got this problem few times, but not like every lap of course. and again - we had track prepared car with 275/275 semislick setup, on large brakes etc.
full 100% solution we made later - our enhanced dct pan, with anti-starvation partitions inside. with it we didn't get any issues at all, even on track days.
so, for street cars i'd recommend to use +1 liter as simplest solution.