I've never heard of GainsWave before, so
I had to google it. It seems to be more useful for overcoming erectile dysfunction than for PE.
I would rather put my money into known supplements like L-arginine and L-citrulline (which help in the creation of nitric oxide, which is necessary for maximizing erections) or Tongkat Ali (which is a natural testosterone booster), and use known manual methods of PE, than use anything like VigRX, which looks like snake oil to me.