I have two Cecilio CEVN electric violins and read the "Silk Purse" thread of another violin forum on methods of boosting the performance of the piezo pickup.  I learned only half of the length of the piezo pickup is active, and that you want the active half under the G side bridge foot (easily determined by removing the bridge and tap the pickup with a small screwdriver while listening to the output with earphones).  

The second problem is that the black plastic bridge base that the piezo pickup sits in is longer than the pickup and is secured to the violin body with two screws.  The screws are often off axis to the violin body top and generally do not provide an ideal solid surface.  I solved this issue by machining a new cherry wood bridge base that I secured with thin 3M (tm) double sided tape.

I made more than I will ever use and would be glad to sell my excess to anyone that wants them for $7 each (including shipping in US).  The base is very thin (a few 0.001th of an inch) and will not affect your existing bridge height.  The base has been bored with an centered oblong hole that matches the plastic and I provided the double sided tape.  I stained them ebony and provided a sealer.  The existing piezo cord is provided with a connector so no soldering is involved when you replace the base.  

I did not provide a picture of the wooden base since a very small black block is not going to provide any meaningful contrast or information.  My base has nominal cavity dimensions of 1.50" long, 0.285" wide, and 0.216" high.  In my experience, this is adequate to fit the piezo but a sliver of bridge foot base may need to be removed for it to fit.  If you don't want to mess with the bridge foot or want the base in the natural cherry color, let me know and I will make another batch to match the Cecilio pastic base length of 1.690".

No clue on how to exchange purchase or shipping information yet but I figured I make the post and see if there was any interest.