An ungoverned 500E will reach 165 MPH, which is also redline. With a gearing change it will go 175 MPH, drag-limited. Only you can decide if the extra 10 MPH is worth it, but I'd see if your car even has a speed limiter (I know several 500E owners that claim their cars are unlimited).
Apparently an ASR defeat switch is not so easy to create, which explains the cost of these devices. You can elect to defeat ASR by disconnecting the front wheel speed sensors, but in doing so you also kill ABS.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car