Replacement speakers for 2007 Tundra with OEM JBL audio

I recently bought a 2007 Tundra with the factory JBL audio. Can I just replace the OEM JBL speakers with aftermarket units? Not looking to spend much money but hoping for better sound? I have read where some of the speakers foam surround will disintegrate over time on these JBL speakers? Simplyspeakers.com sells replacement foam surrounds for the front door and rear sub speakers. Has anyone done used their diy kits?

 

Main thing to know is the door speakers are not normal 6x9's, and I believe yours may be 2 ohm.

There are adapters you can get that are inexpensive and will mount just like the original speakers and you then can mount a set of standard 6x9's. There are also adapters for 6.5's.