Installed the Flipper Fidelity Meaty Beaty Big and Bassy speaker system kit in my Met Monsters today. WAY better than stock. Way better than stock with a Polk sub underneath. Since the cabinet speaker is basically a big 3-way, it balances the sound out nicely. If you are looking for some better sound out of your Met, give this a shot.
Oh.. and one other thing.. I have always wondered why the sound in my Met sounded "off." I can tell that Stern didn't do that great of a job mixing the soundtrack - especially the bass on the spinners as it's too much, but what I am talking about is something different. It's hard to describe, but something just wasn't right. During the installation of the flipper fidelity system I discovered why. The 2 backbox speakers were wired out of phase from the factory. So check your speakers and cabinet speakers to see if yours are too. The wire with the white stripe should be negative and the wire with the black stripe should be positive. The terminals on the speakers have a "+" and/or a "-" to designate the polarity.
However, that being said, it doesn't matter how you wire the speakers as long as they are *all the same.* In other words, you can wire the black stripe wire to negative, as long as ALL of the speakers have the black stripe wire as negative it will be fine. Or vice versa.