I'm in the middle of syntherol cycle myself at the moment. Definitely works, im up approx 2 inches on my arms so far.
It quite painful at first and each time you increase the volume of injection the pain comes back, the rest of the time its more of a throbbing ache.
Also RE: synthol and other products im pretty sure Syntherol is the only SEO that is made in a real lab. You know exactly what is in it, i think thats reason enough not to use anything else when you have to 'search' to find out what is actually in the other SEOs