Wasn't L-Tyrosine a part of the ingredients in Muscle Synergy at one time? Tyrosine can be a great pre-training boost without caffeine. Will it be coming back?
Since you wouldn't want that prior to bed and some people take MS then, you could have maybe 2 different formulas?
I guess it can always be taken separately. NOW has good prices on individual aminos.
Another great addition would be pycnogenol. Try adding a couple of caps of this to your MS dose and see what you think. It really seems to amplify the Arginine/Pump effect.
Thoughts?

Yes, muscle Synergy has undergone a few differnent "identities" since its introduction a few years ago. Each incarnation of MS seems to have worked the same for me, although that is most likely due to the same dosage of L-Arginine that each "incarnation" had.

More L-Arginine will most definetly give a better pump via hemodilation and nitric oxide release effects. A lot of studies have used as much as 20g of L-Arginine to induce that sort of effect....

Just something to think about: l-Arginine is a stimulator for viral herpes outbreak. The more L-Arginine in the blood, the dormant herpes virus likes to horde it and use it for outbreak purposes.... If this is a concern at all, try using Density in conjunction with the MS.

I personally have been having some killer pumps from Density along during my workouts!