We can all agree that this is not a kit that you get just to be cool but because you have exhausted the limit of the stock transmission. By all means this is not for a everyday street car.
From what I see of PPg's site they dont offer R154 kit but just W series...
As far as the V160...good luck finding one cheap (3000 or less) then hope that it wans not raped. Then Get new drive shaft, cut hole for the shifter, fabricate trans mount, get new clutch (at least the disk or more) and then hope that if something hapens you can find parts cause the dealer dont sell them... not to mention that it is close ratio trans and that is the last think we need. It is not a 5speed with overdrive in our cars. its more like shifting five times where you used to shift 4. Every time you shift you drop boost and slow down...
The only other cost effective alternative is a T56 but aggain it requires lots of fabrication and new parts. You would loose some money on the parts you curently have after you sell them to offset your cost. You have varaety of gear ratios availiable from 3.40 in first to 2.66 and everything in between for fist second and third fifth and sixth are independant from the cluster shaft and can be customised individualy. Its nice dont know if it fits =). and i dont want to trow $2000 on a trans just to find out swap doesnt work.
The bolt on option is by far the easyest but it may cost little more for the convinience.