i got the same problem, mine slips like crazy 2nd n upwards. started after the midnight cruise. im getting a heavy duty installed by my local mechanic, around $600, he put in a heavy duty on my old r33 gts 2 yrs ago an it was heaps good. i got prices at like other mechanics (ultra tune, midas, etc) n they all say clost to a grand. the only bad thing is ive had 2 wait 2 weeks cos he is busy, n now its getting done on thursday so i cant wait, cos i got a boost controller and i havent got a chance 2 use it yet haha