if you are referring to the customautosound "invisible" radio, i have been using one in my el camino for a couple of years with decent success. you should be able to put it just about any place you want to including the glove box (if you have one big enough) or in the main storage compartment behind the seats. if you have a convertible, you can just put it on the back shelf all the way back against the rear of the compartment. again depending on the year of your car, it might even fit under one of the seats. i would suggest the passenger side if it will fit only because it will probably get less stress on that side. in my el camino, i mounted it in a verticle position behind the vanity "curtain" that covers the spare tire and storage bin area behind the seats and it works well as far as remote reception.
hope that gives you some ideas.
steve