Depends on which route you want to take. The is always P-slin or Anabolic Pump; both are potent nutrient repartitioners. I have not tried AP but I am quite impressed with the P-Slin. If you check out the Anabolic Pump manual you can find information on the effects of both supplements and see if they are right for you:
http://anabolicminds.com/forum/usp-labs/85753-ap-manual.html
RPM and/or Drive are another good option, I'm using both currently and have definately seen an increase in strength, intensity, and endurance in the gym.
Either of these options will give you the 'boost' you desire in the gym and have recomposition effects as well.
Anti-cortisol supplements would be another good choice. From taking lean xtreme, I can say that I definately noticed a leaning effect but not anything out of the ordinary in the gym. Perhaps better recovery but it was hard to tell b/c my joints got pretty achey toward the end of the cycle.
As far as other supplements go, DTHC for example, I cannot comment on their effectiveness for I have not tried them myself. I have heard good reviews tho.
