I installed the Vishnu procede plus meth on my 08 M3 with 6MT. Already have underdrive pulley, catless x-pipe and filter. I really like it and think it adds more power than a tune alone (and it should for twice the price). Have gone through about half a gallon of 70/30 meth/water in just a few days, but I have been doing a lot of test driving. I don't like the standard install so I will be doing a trunk mount for the meth and pump soon. I will eventually dyno to see the cumulative effect of my mods, but since I do not have a baseline, I will not know the exact gains. If it makes close to 400 rwhp SAE on a dynojet, I will be happy. That was the goal for my $2500 in performance mods.
The install takes longer than the 45 minutes claimed, except perhaps for someone who has done it before. For the competent first timer, I would plan on 2-3 hours.