I wouldn’t suggest removing the cover for several reasons. Firstly, the cover is there to protect the fragile coil windings on the pickup and if you accidentally snag the pickup with the string while playing can result in a broken pickup. Secondly, removing the cover can cause the flatwork to get worn and moisture penetrate the coil more rapidly. The moisture can contaminate the insulation on the magnet wire causing it to break down and eventually causing the magnet wire to oxidize and finally break. I would leave the covers on especially on vintage Stratocaster pickups. There is no benefit to removing the cover to get more output from them, and they are very likely to be broken when you start messing around with them.